Double Bass Bass tuner slipping or hysteresis question

[layrepairs]

My son's bass has an issue with one tuner. I'm going to try to get a good high resolution close up of the machine but basically it slips and hence is very difficult to tune. The issue is not new but a big source of frustration. Takes too long to get it right.

My feeling is this is due to the "worm gear" wearing over the years but I'm far from certain. Nothing is actually broken or obviously wrong.
The plates are screwed down tight. BTW: the attached picture is a few years old. Sorry, I don't currently have the instrument.
All four look about in the same condition. The worm gears may be some sort of brass coated steel.

It has had these strings for some time:
Two Spirocore (E & A)
Two Obligato
Set from Upton Bass

Any comments about how to repair the gearing would be appreciated. I was wondering about a very thin Teflon washer under the gear or some modification to tighten it up. Take off the whole plate and squeeze down those little worm gear U "bearings" tighter?

Thanks as always

 

[Don Hergert]

The image provided shows two tuners, for the D and G strings (in RH 4ths tuning setup). Which one is slipping?

Also, have the gears been oiled recently?

 

[dperrott]

It is rarely the gears but how the strings are put on the pegs. Strings can slip if there is too much windings on the peg. If the strings are real old and chewed up they can slip. If there isn't a nice and neat lineup in the peg box they can slip. Always tune up to pitch never down to the pitch. I have many clients ask about it and its always been about the strings and not the gears.

 

[DoubleMIDI]

With a bit longer strings I always first wind away from the nut slot for a few windings, then quickly diagonally over the windings back behind the peg hole and then towards the nut slot. The diagonal part fixes the first windings so the string can not slip through the hole, no need to let the strings stick out of the hole and the string path in the pegbox is as straight as possible.

With shorter strings I bend the out sticking part parallel to the peg and wind over it several times to fix it.

So check if the peg is slipping or the string. Easy with two people.

 

[Ketbass]

Sounds like string slippage. I’m going out on a limb here, but is it your D? Like a right hand person tying their left hand shoelace, my D always slips due to?? But an easy way to check it and snug it is to tune it up then pull up on it and gently lower it back down. Check the tuning again. If it’s out, then chances are it’s the winding process. Sometimes doing this will set it tight and problem solved after a couple of pulls. Other times, I have to unwind it and rewind it making sure the silk wraps over itself neatly, but also not to many times. To much string can never quite tighten down. It’s the same when I do my electric basses.

 

[fdeck]

On both upright and electric bass, all of my tuner problems were solved by "take it apart and put it back together again." I would invariably find the thing that was loose or in need of cleaning or lubrication.

 

[james condino]

Start out with a bit of lubrication. Tri flow, or even better one of the dry (er) bike shop lubes- on the gears, the worm, and get it inside the button shaft collars. Then clean it all off. A lot of these mid 20th century German tuners get a little loose after half a century or more; the shaft collars are essentially pressed in. Use a small plastic mallet and give them a few taps in the right place to tighten things up a little. LIGHT taps, not beat the %$#@ otta it! NO metal hammers...

I have owned more than a few basses where the tuners were just old and worn out. The solution to slipping was to sling a hairtie or two around two shafts to tighten up just enough for the rattles to stop.

 

[layrepairs]

Start out with a bit of lubrication. Tri flow, or even better one of the dry (er) bike shop lubes- on the gears, the worm, and get it inside the button shaft collars. Then clean it all off. A lot of these mid 20th century German tuners get a little loose after half a century or more; the shaft collars are essentially pressed in. Use a small plastic mallet and give them a few taps in the right place to tighten things up a little. LIGHT taps, not beat the %$#@ otta it! NO metal hammers...

I have owned more than a few basses where the tuners were just old and worn out. The solution to slipping was to sling a hairtie or two around two shafts to tighten up just enough for the rattles to stop.

This is sort of what I was considering. So, I would unwind both strings, remove the plate screws and try to make the worm gear collars tighter? Take it off for sure, right?

 

[layrepairs]

This is sort of what I was considering. So, I would unwind both strings, remove the plate screws and try to make the worm gear collars tighter? Take it off for sure, right?

So, that is the E turner with the string removed. All the original windings look well done and were installed at a very professional place several years back (ten years ago?). Some of the center screws were not tight but making them completely tight pretty much makes the tuners bind. I slightly polished the inside of the E string gear by rubbing it slightly over my plate glass with 1000 wet/dry, the so called scary sharp method for tools. That my have helped a bit. Still, running the screw in all the way binds and then backing off very slightly seems to "best" but really seems incorrect to me. I think for typical machining, such a gear would sit "hard" against the base under the square of the tuning peg. So, that behavior seems like it is tightening against the plate, not the seat of the actual "peg". Adding some sort of washer under the gear would only make that behavior worse I think, even if it reduced the friction between the gear and plate.

Some other observations:

With the gear off on the E string, the turner worm gear has a slight amount of play. This doesn't seem to be excessive wear to the little U collars.

The G and A seem to have the most jerky behavior but I haven't taken those strings off and done the same tests.

I don't see any extreme wear on any of the circular gears or the "worm gears".


Do I need to take off both plates, brasso the gears, buff the backs, clean and lube it all, rewind the strings, etc?

Thanks for any comments