There's a very large available selection of knobs that will fit the smooth-shaft controls. I've got a new 55-02D and personally, I don't think the Lakland knobs themselves are any great shakes. They're adequate, and do the job, and won't fall off onstage, so I won't bother to replace them any time soon, but they aren't particularly attractive (to me). Allparts, Stewart-McDonald, BestBassGear, Musician's Friend, and others, all sell good aftermarket knobs. And these folks:
http://qparts.com/index.php?cPath=20
make a wide range of knobs for smooth-shaft pots. I like their abalone-topped dome knobs, but maybe you'll prefer their skull-shaped or chicken-head knobs.
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(Potentially wandering off-topic.....)
I once added small 'dimples' as position marks to four smooth dome knobs with a small drill press. I used a ~4" long strip of denim wrapped around the knob to clamp it in the drill press vise without scratching the knob. You have to find the right angle to tilt the knob to get the correct angle for the dimple - I think it may have been about 28 degrees for mine, but this was several years ago so go with what looks correct. Now, if you use a small drill bit to make the dimple, it will bend and dance all around on the hard chrome surface of the knob. Instead, what you have to do is use a much larger drill bit so it won't bend and just barely start to drill a hole in the knob, just begin to penetrate the surface, and then stop. Put a tiny drop of model paint in the dimple w/ a toothpick, let dry, tilt the knobs so the dimples are level so the paint dries smoothly, and you've got some nice-looking position marks.
Note that it is *extremely* easy to mess this up and drill too far and ruin the knob. So I can't take any responsibility for anyone damaging or destroying their knobs - but it *is* possible to do a fairly nice looking job of it if you're extremely careful. Best o' luck.
