Ok, so I checked both a Tron and Satans Hollow. The B2 location is actually a 6116 Ram chip. I replaced the Timber 6116 with a known working one and it made no difference.
I also swapped out the Z80's on the CPU board and with no change.
Double check the voltage on your power supply....try increasing it a bit, if possible. I've had two MCR boards give "false" RAM errors, due a voltage being slightly low.
-Mark