Life expectancy of ASR-10 SCSI controller?

Seems like the scsi controller is going bad on my ASR-10. I keep getting "disc not responding" messages no matter which device I select. (I have a hard drive, zip drive, and cd-rom in the chain). Are these prone to failure and anyone know where I can get another one cheap?

I have an ASR 10 rack and, in more than 15 years, have never had such a problem. All I can suggest is to connect one SCSI device at a time and see what happen.
Good luck