Trimble Base/Rover problem

I have 2 Base/Rover systems, both Trimble, one base is a 5800, the other an R8. I have always been able to use either rover with either base. My controller blew up a couple weeks ago and had to have some board in it replaced. Got it back, and now, I can set up either base and start a survey, no problem. However, when I start either rover, they will both initialize and work fine with the 5800 base, but will not initialize with the R8. They stay in float with that one, or will occasionally initialize with a high RMS and large H and V differentials, then lose initialization. Radio connections says it's fine, I can take that base off the tripod and put the other back on, and everything works. Any ideas?