I have an older MTH PS/1 EMD F3 that operates intermittently ( pic attached). After charging the BCR for three minutes and cycling the engine from neutral to forward, the engine will rev up as is if it's moving but remain in a stationary position. If I push down on the top board, with my finger , and apply pressure the engine will move forward for as long as I hold it. I have inspected the board in depth in all of the prongs are inserted into the bottom board and I cannot find any loose wires that have become unsoldered. The boards look intact as well. I have applied pressure at various points on the top board and cannot find a specific spot that always fixes the problem other than applying pressure as a whole. I have tried using wire ties to compress the two boards together but it isn't a sufficient amount of pressure to make the engine work successfully every time.
Also about one out of six times the engine will start up in an unusable error status. When this happens, The engine will have the bell ring continuously until I turn the power off totally for a couple of seconds and then try again. This error tends to happen if I apply to many volts between neutral and forward.
Not sure if these are indicators that the board is fried but any insight or help would be much appreciated. The fact that manual pressure makes the locomotive work seems to indicate that the boards are OK, but I'm not sure.
Thanks much