We had a cust send in a TDS3012B which won't trigger off any signal
less than 2.5 divisions in DC coupling, and .7 divisions Noise Reject
for signals below 50MHz, up at 100MHz the sensitivity is a little
lower, say 3 div & 1 div, respectively. The manual states
specifications as .6div for DC & 3.5 times the DC limit for noise
reject below 50MHz, going up to 1 div for 100MHz. What could have
caused this? Noise Reject has higher sensitivity than plain DC
coupling?

We ran through the adjustment procedure, it passes without problem,
all self tests pass, and the unit passes all other sections of the
performance verification. We took the scope apart to make sure it
wasn't anythign loose, but it looks like basically a single board
deal, nothing to come loose.

Any ideas besides $1200.00 to send to Tek for repair?

Thanks,
Steve