I have 3 saber 1000 cnc's with 850sx controllers. From time to time, for no reason, 1 or 2 tools will loose its tram or TLO as much as .040 to deep. If we retouch off the tool or tools they will still be up to .040 to deep, however if we retouch the tram they will machine to the correct depth. Keep in mind this does not happen to all the tools just 1 or 2 while this rest of the tools machine to the correct depth This does not always happen to the same tool but once it happens it will keep happening to that same tool until whatever it is corrects itself. In some cases the machine will go months with out any problems then as the problem will raise its ugly head. We have gotten to the point that we retouch tram every morning when we start the machines just to safe but this doesn't always last all day on some days.
I also have a saber 500 and 750 with the same control and have never had this issue. All but 1 of the 1000's are fanuc drives and the 1 is kollmorgen drives so this tells me its not necessarily a drive issue.
Has anyone had this same issue and if so were you able to fix it and if so please share.

Thanks,
Brian