Problems with a HP4815A

[joaquin]

Hi from Spain:

Today I had a problem with my loved HP 4815A

RF Vector impedance meter.

Here are the details:

All is beign OK and suddenly the coils had phase -90 like a capacitor,
and since a time later
the light of searching in the front (Phase lock loop) always is active
and fluctuating,
I will be very grateful if some expert would can give me some guide
before starts my repair work.

Thanks in advance.

Joaquin.