Philips / Fluke PM5138

[Devilsea2001]

Hi guys,
My name is Jo, from London UK.
Unfortunately my baby PM5138 doesn't work anymore, it power up , display ad it h and dial are ok, I can change any parameter but no it out on the front BNC at all, only noise .
If I change mode selecting PCK and changing the symmetry, I get a.perfect 1K square wave on the output.
AlI checked the psu and all the output voltage are ok, clean and stable.
Do someone have experience on this lovely unit, any help is very welcome.

Thanks for your time.
Happy new year

Giuseppe