Strange 737 trim behaviour

Dear Pit builders colleagues,

I've a strange issue with my trim. If i trim to the most outher value the trim starts to go up and down like a switch contiuously switching...
If i trim back to neutral position the effect disappears. This happened to me often when after take of during climbing out.
The following trim hardware : GoFlight LGT (Rotary Encoder brought to pedestal trim wheel).
Software : FsXpand, FreedFD, PM, FS9.
The trim is assigned to the switch on the yoke (Saitek) and to the trimwheel.

Did somebody experianced a similar problem?

How did you solved this?

Looking forward to some advise.

Thanks in advance,

Regards from Bas

KLM077