914 wastegate servo issue

Hi everyone,

I seem to have a random issue with the waste gate servo on my 914 UL (TSN 200hrs).

At power on TCU lamps self test for 1-2 sec, than switch off.

Wastegate servo performs self test from fully open to fully closed position, but then seems to overturn into the closed position and gets stuck there. ( image 1 in the attachment shows servo in the stuck position).

Yellow TCU warning light starts flashing, as it should.

If I power off and power on again the servo stays stuck and yellow TCU light starts flashing right away.

To free the servo up again I opened it up very carefully and reassembled it.

After that it worked for some time until randomly it turned too far and got stuck again.

I think the servo turns way too far into the closed position sometimes, but I am not sure about the cause:

Is my wastegate cable too loose?

Or is this an issue with the wipers inside the servo?

I also checked the nominal resistances at the servo connectors according to Rotax Maintenance Manual Heavy  912/914, 78-20-00 ( see image 2 in the attachment):

Connectors: E-C: 5,00 kΩ > ok

Connectors: E-D: 5,02 kΩ > way too high, should be 0 to 70 Ω ! 

Connectors: C-D: 5,6 kΩ > ok

Connectors A-B: 10 Ω > ok

Did anybody experience this issue before maybe and know a solution?

Many thanks for your help everyone!