Geof Wingham has documented a very comprehensive program to improve the tracking of his 12" GPS.  His charts & comments documents the periodic error before and after the installation of Buck's Gears.  Geof's comments are highlighted in red.

Red Line original PE Error of LX200GPS 12" when first placed on a wedge - once I had cleaned the crap and aluminum filings off the worm it started to show 3 distinct cycles as it should.

I tried PEMPro to fix LX200 but it was a waste of time - replaced all the gears with Bucks gears and tightened up and adjusted what I could - it gave a lot smoother PE though it was still high.

Once Bucks gears were in PEMPro had a chance and I was able to reduce PE to around 16 arc sec peak to peak - WOW - Says a lot for the quality of Meade Telescopes. Especially the mounts.
 

Geof started out with what was obviously a very bad drive - one unusable for imaging even with guiding.  This isn't uncommon.  Only after Buck's Gears were installed (and all the mechanical tune-ups included with a Buck's Gears installation were made) was Geof able to make meaningful PEC corrections.  PEMPro gives nice informative graphics but I've found Meade's PEC training to be just as effective.  It's necessary to run through several PEC training cycles to optimize drive performance and I don't know if Geof did that.  His periodic error is still a bit on the high side, but with the very gentle slopes exhibited over the scope's 24-minute period quality imaging is now possible.

Geof's full PEC correction procedure may be found at http://www.pbase.com/loc46south/equipment