Thanks for that. Since I posted to the forum I have 'messed' around with the device and picolog a little and it does seem to be an intermittent fault. Sometimes the device is recognised and sometimes it isn't. I think you are right, the best bet is to get it back to you for evaluation and repair if possible. It is a fundamental part of our system so we will need to know if it can be repaired or needs replacing as soon as possible.
Once again, thanks for your help. I'll contact the email address you suggested and get the TC-08 back a.s.a.p.
Medical Physics Department
Queens Medical Centre