Yep sure do, I have the standard 20% tol 500K CTS audio pots and the 10% tol. 500K CTS audio pots with brass threads and brass shafts. Shoot me an email at jonesyblues@yahoo.com for prices or if you want to place an order. Thanks, jonesy
If you have a multimeter (see my video in Tonefreaks) you can use that, and also if you feels like it turns hard, cuts off faster than normal or it is scratchy that is another way to tell.
A cold solder joint can cause that, or a bad pot will also do that (from over heating when soldering to the back) or something hot may be partially touching ground. Also if connections are switch are pinched they may also cause a slight buzz or humm.