A-B analog outputy card trouble

I have a PLC5/40E with 1771-IFE analog output cards. Once in a while the card will "freeze" and a point will only put out 4ma. The PID will appear to be working, there is no fault indication exterinally at all.Register N14:6 is the actual control variable from the PID instruction, and it follows the manual control command, but the point will put out just 4 ma. I have to toggle the PLC5 with the key to get the card working again. The BTW instruction to that card does set its .ERR bit. My questions: what can cause a card to fault like this, and, how can I reset the BTW without toggling the whole PLC5?

The 1771-IFE is a input module. Do you mean 1771-OFE2 ( you did say 4ma)
Is the card in the resident rack or remote I/O rack? Where do you have your last state jumper set? Where do you have your rack switch 1 set.
Can you post your code so someone can take a look just incase there might be something there.

The manual if you don't have it:

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1771-um030_-en-p.pdf