Do powertap hubs wear out? aka Cycleops

After many years of faithful service, my Powertap PRO+ hub (15mm alloy axle) has been throwing out completely garbage data for the last few months.

The hub was always super reliable and never required recalibration, now if I recalibrate it'll sometimes give out sensible numbers for a little while but soon goes back to throwing garbage data, usually stupidly high power figures.

I'm just wondering if anybody else has had similar issues and worked out what the problem/fix is?
The bearings and axle are all good, changing batteries doesn't help either.

I could try spending £100 putting to put a G3 cap on it, but it seems more probable that the problem is something more fundamentally mechanical (stress gauge coming unbonded or plastic sleeve worn perhaps).