My STSe 3501-01 BKSU has failed. It starts up OK, but there are no digital phones from the mother board(Sta 100-107). Sta 108-115 work fine from a DTIB. The phone programming and hyper terminal programming works fine. I have experienced the same problem on an XTS 3001-00 24-line digital card where the first 12 lines failed (Sta 108-119), but the next 12 are OK (Sta 120-131). Also on an XTS 3001-00 CKIB board (Sta 100-107) where the digital lines don't power the digital keysets. The system is the digital key set displays are all blank, like they are unplugged. Is there something that is fixable here?