The S-12 did not run too good when new so I tried a few things. An old smith advised me to break it in by using a q-tip to put some valve lapping compound on the offending parts. I did just that, cycled it a few hundred times, cleaned it all up and went to the range. That seemed to help a lot. Tried the "gunfixer" plug and that was about worthless.
Getting ready to do the mod now, hopefully it will go well. Any tips and advice greatly appreciated.