I have (2) BG 4004 turntables and the pickup arm drops at different rates, one is perfect and the other is too fast.  I adjusted the damper cylinder screw and it is turned all the way in.  This did help but still too fast.  Is there another adjustment that would help or is the cylinder bad?  If it is bad can it be reworked?

Probably lack of a decent seal in the cylinder iteself. This would have originally been accomplished with some sort of hydraulic based oil I believe.

Carefully pull the plunger out (after releasing the upper arm from pivot), give it a good clean, then use a small drop of quality sewing machine oil - not 3in1!!!

That should sort it!

Sounds simple enough, Thanks

This was the simplest adjustment to this turntable ever, it looked more complicated than it was. Just as you said, clean piston, oil it.  10 minute repair, THANKS

Nice to get feedback, glad all is working again :)