Hameg HMO3524 channel 1 repair

[Noy]

Hi guys,
i got a HMO3524 with 3 working and 1 non working channel.
Channel 2-4 is ok. Channel 1 is clipping anywhere at the max (not shown on screen), it is independent of DC/AC input select and 50 Ohm input selection also.
Only if i put it into GND selection its shown on screen. I opened it already and I try to check the difference between channel 2 and channel 1.
Until now i found out that it is overdriven. I will post pictures and more details tomorrow. But has anybody any suggestions, what it could be?

[Noy]

OK now some new information...

I took a thermal image from channel 1 and channel 2 (see attached).
Difference is currently the PMBFJ620 JFET himself the hot (SC70) package is ok. But anything put the channel into clipping, it's totally oversteered.

Here are some pics:

[Noy]

Replaced the Opamps and its back working...

Only the small part (dark grey) left to the SOT-23-3 beside the blue pot mold a bit as i touched it accidently with my solderiron...

The channel  works and it looks like everything is ok but what could the part be? It mold directly like it would be out of plastic...