I have a TAC 50-04 bank of 6 elevators and the number 1 unit is stuck in fire service. I have replaced the CPUA board and had it running, but it returned to stuck in fire service state. FS1L output stays hi and will not release. I have all the proper I/O's to reset fire service as the group will reset if I take this particular car out of the group. 2-6 will run all day long until I reattach car 1 to the group comm. Any ideas what else may be causing this issue? Thanks for all your help!