Problem READING CV's but not every loco?

[PJ_model_trains]

I am trying to read the CV's on a Bachmann Branchline 31-213DS Class 6P Patriot 4-6-0 45504 "Royal Signals" in BR green with late crest. DCC Sound Fitted.

 

It goes to CV7 Manufacturers Version and attempt to read throwing up error... repeating etc.

 

I

 

have read CV's on another loco before and after trying the above and made sure rail and loco wheels are clean and in good contact. I have also changed CV on another loco and wrote it back to the loco no problem. I have also tried by applied extra pressure

 

on the loco to rails but it makes no difference.

 

Any suggests please?