[time-nuts] HP 5065A, no 2nd harmonic.

[cdelect at juno.com]

With that offset either the oven set point has changed or there has een a
component value shift in the oscillator circuit. 

The easiest way to test is to stick in another 10811 if available.

You could also install one of the original  105 style oscillators if you
have one.

Cheers,

Corby