[Test-Equipment] HP3311A with "issues"

[Barry]

My 3311A gives very non-linear curves on the high range (100KHz to 1MHz).  Triangle waves look more like a sine wave and square waves aren't square (the leading edge is very curved compared to the falling edge).

Anyone seen this before and have an idea of what's wrong?  Power supply (+/- 18V) output looks pretty good (low but within tolerance) with ripple (within tolerance I think).

Any ideas what to look for?

Thanks,
Barry - N4BUQ