tajima tmex-c1201 not sensing thread breaks

Looking to see if there is anyone that might be able to give me some advice on what to do or where to look that i havent already tried. Just got this machine, we already have one of this model and then also a 4 head, so i kinda know a little bit on this subject. The new machine wont sense thread breaks. with the machine unthreaded it'll still run. I've cleaned the brass contacts so those are all clean. I've removed the back panel and unplugged the two connections back there and air sprayed those out to make sure there was no just on those. Air cleaned the brass on the back side around the plugs. Still nothing. runs without the machine being threaded. runs designs great, but there again no sensing thread breaks. Anything i've over looked or forgotten? is there a setting on the control panel that i'm over looking??? Also this machine does not have the manual design trace option On the D button on the main control where all my others do. this is a 97 machine along with my others that do have the trace option..how could this one not? any help would be great! Sorry for the long post...Hoogie