Aperture issue with Pentax FA 80-320

I recently picked this lens up with a bunch of other gear and was going to E-bay it but it appears to have a problem with the camera body unable too controll the aperture, all I get is F.... in the top LCD screen.

The lens autofocuses and locks on with focus confirmation but aperture control can only be achieved by using the aperture ring.

I have tried cleaning the contacts without success and I have the camera set too "permitted" for use of the aperture ring. I have also tried it on 3 other bodies without luck K20, K7, and an MZ7 film camera, all with the same result, is the lens a dud or is there an easy fix, it appears to be an electrical problem but where do you start looking ??

Thanks in advance.

Probably one of the contacts has come away internally. Fixable but it'd probably cost as much to mend as a working example would be worth anyway.

If it were me I'd stick it on eBay anyway and just highlight the defect - I've no doubt you'll still get quite a reasonable price for it as-is.

Unlike you to pick up a dud Clarky...