PT6A Np spikes. Experience?

[Kinger]

Anybody come across random Np peaks in service? Prop running at approx. 2000rpm, but after a period in flight, the gauge just jumps up with no lever input.
All other engine indications fine and no prop hunting.
Lots of investigation gone on, mechanical and electrical, and installing a known serviceable but older Np tacho gene has apparently cleared it. Four new ones from the same batch all failed to shift the defect.
I don't need fault finding, just wondering if anyone else has seen this issue, and if so, would you be willing to share part details.
Cheers,

[Perrin]

Had lots of bad parts out of stores in my 50 some years changing them. One which really peed me off was this, raining hard with wind at Glasgow a ATP with hyd pump problem changed two times and both were low output along with very heavy cowlings that was when I took early retirement.

Keep them up boys:ok:

[ivor toolbox]

Hi Pete, glad you're still around.
Seasons greetings.