I have a blast freezer with Bitzer S6F-30.2Y compressor. It normally goes down to -35c with 1.2 ton of fish in 8 hours. After service by an unqualified technician, it now takes 14 hours to reach -14c.
Parameters are:
18.5Amp
Discharge=224psi
Suction=8psi
Intermediate Pressure=89psi
Superheat bulb temp=34.7c
Oil pressure=94psi
I also have a little ice on the suction cup at the entrance to the cylinder, but not on the cylinder head.

I need help getting the system back to normal. Do I need to adjust the superheat or is it something else?
Any help will be appreciated. Thanks.