Gyraf g14 hum

hi everyone,

hope this is the right place to post.

Have a loud 50hz hum in my g14 (old version, no solid state); something like -80db at 50hz. The g14 is by far the worst unit in my chain regarding hum.

Tried placing it around in the chain, isolating it from other units, did not help.

1) what values are to be expected from the g14 regarding hum?

2) did someone experiment with rotating the power transformer? did this help? important: if i try it myself: if the power is off, is there any danger while doing this?

Thanks!