Regurgitation problem

[Freakie_frog]

Sorry I don't know what P/K or F/T mean?? We defrost frozen rats to feed

No worries.

P/K = Prekilled i.e a rat you purchase like dispatch yourself then feed off
F/T - Frozen Thawed.

It's possible that either the rodents are expired, freezer burned, or not completely thawed out and warm all the way through. Barring any other health issue like a substrate impaction or GI trac issue then I'd look to the feeder. Assuming that the temperatures are still with in the proper range. Heat mats and elements have been known to slowly go bad and thus allowing the temps to drop or spike at times thus causing a regurge.