[Test-Equipment] HP-3335A no output...

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I have an HP-3335A Level Generator which was placed on a shelf, unpowered, a few years ago.
At that time it worked ok. Today I have powered it on again, apparently all is ok, the front
panel behaves as expected, but there is no output, nor from the 50 nor from the 75 ohm
BNC connectors...

Changing the level from the front panel produces some relay clicks.
Any clues on what it can have happened, and what to check ?

TIA

Alberto  I2PHD