SR, is there a reason why you didn't upgrade all your pots while you were at it? I was considering it for two reasons. I thought for very little investment I could upgrade them to 500K, and also I can more easily match the control knobs (I'm probably going to change them).
On that topic, do you happen to know the type of shaft the stock Jag SS has? I've never had one off.
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FTR, 500K pots are not necessarily an upgrade over 250K pots, and large pots are not necessarily an upgrade over small ones.
500K pots are generally used when a higher impedance pickup [one with more turns of wire and a reading of more K on your ohm meter if you measure them] has been chosen by the maker of the instrument.
Gibson humbuckers are a good example of this, whereas the vast majority of Fender instruments are not, due to their predominant use of single coil pickups, and even a P split pickup is not all that high of an impedance, compared to a typical dual coil humbucker such as those on a Gibson Les Paul.
It's an issue of impedance matching, between the pickups and the pots.
If your pots are working properly, leave them until they do not.
A 'Balance pot' could be considered an upgrade, but simply an alternate make or model of volume or tone pots, not.
If you absolutely must spend money on something, and the money is burning a hole in yer pocket, and causing you
PAPD [Parts & Accessories Purchase Disorder], consider strings, pickups, and tuning machines.
Those items are where some benefit might be noticed.
The one exception on the pots resistance is with active EMGs [and any similarly designed pickups of other brands], which usually come with [and need] 25K pots, due to the low output impedance of each pickup's internal preamp.
Again, it's for proper impedance matching.
Also, the electrical value of a tone capacitor [also generally included] needs to be much larger to match this as well, same reason.
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Oh, and while I'm on a myth-quashing roll, let me add that those pretty looking
orange Sprague capacitors, while being a good quality component, work identically to any other brand, if they have the same electrical value [that's the number of
uf or
pf] stamped on them.
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