My RT-909 has been refurbished (by me) . The forward play has always been a little lower than reverse play . When calibrating the trim pot had to be turn full on .The heads have been relapped and edge slots at JRF. The tip depth of the heads is 0.008 and 0.006 . Excluding the head what else could cause this attenuated output? The deck plays and records but sounds better in reverse play.I have cleaned all the switches a few times. I have a set of new heads but I want to make everything else is operating correctly . I'm just starting on this project ,the deck is still being used. This is the fact finding part. Any tips or suggestions greatly appreciated , thanks in advance