Kent,
The SAMS valve you have in the reverse hole is the same one that was initially in forward and you disassembled and cleaned as I understand it? If this is the case- my bet is that the reassembly did not go well and now it is sending pressure to the reverse pack. The whole set up was a PITA, we use to switch spots as you did in the late 80's and of found defective, replace. Never any luck cleaning them. I did several conversions those days, some in the field even. The SAMS valves were pulled and aluminum blocks were slid in their place. I don't think you can buy a SAMS valve any longer. Maybe Hader can repair yours? I actually had a good used one at the shop, might still be there.