foxboro 761 CSA stuck @ 48%

I have a Foxboro 761CSA that gets stuck at 48.7% output signal in manual and will not move. It will not work in auto. Cycled power, stepped through the program to check all parameters and everything looks good.

This happens every once in awhile for this controller in the control loop that does not operate to often. When it does work it works fine but for some reason it just locks up, again. We had a spare model and swapped it out and it worked for a few months but then it to locked up. It was working last week even. Input signals and output signal are verified and work good. Changed out the 32 position terminal block as well and same issue. this control loop needs to be in service and have exhausted attempts. I have the manuals but there are no real "troubleshooting" topics in the manual for this type of problem. As important as this process system is supposed to be the company doesn't want to spend the money to upgrade it, even with the deep pockets that they have. I am stuck with trying to get this thing working.

Has anyone out there ever come across this problem? Any suggestions would be most appreciated. Thanks.

Does it happen randomly or only when you switch to manual

randomly. however, I may have found the problem. my theory is that we may be having power issues causing the controller to default to the 'workstation' of the W/P and is locking it up there. we do not use a computer workstation anymore so the controller needs to be in 'panel' mode 'P'. That also my be taking the controller out of cascade bypass as well since two inputs are coming into the controller. I will be testing this theory out tomorrow morning when I come back in.

Thanks labeledas.