HP8590L spectrum analyser CAL: SPAN SENS FAIL

[Bjoern]

I bought my spectrum analyzer second hand recently and had to replace two tantalum capacitors
before I was able to start it up.
When I now try to run the self cal mode i run into the CAL: SPAN SENS FAIL error.
What is the likely cause for this problem ?
Could I get an electric schematic somewhere ?
When I connect a sine wave signal generator I do not seem to get a sensible signal.
Since I have never used a spectrum analyzer that was working I am not familiar with its settings which doesn't help in troubleshoot either.
I suspect that the error is caused due to age as the damaged capacitors in the +15volt line suggests.

Whats the advice ??