Having a lazy cyber/magic eye would be annoying.
Not familiar with Harp, but you have a cool idea.
Easy ruling is to have it require maintenance for a duration of use. Needs to be lubed, tweaked and tuned 1/wk, month, whatever. Harder ruling would be -5/week.. etc (in whatever skill it affects) until maintained.
If you're into tracking these things, give it a penalty for every failed roll involving that cyber part. -5/ failed Observation (if that's a skill used in the game).
The PC game was very malleable for you to customize the code. I had shrunk the annoying compass in the last game to 1/3 the size and removed the graininess to his eye while zooming. (Also reduced that annoying billowing fog between panels.) I remember other people liked the grainy, snowy image and some changed the color of zoom images to look IR.
It would be fun to have a list of malfunctions that can occur if the cyber part isn't kept in tune. Cyberspace had some good rules for this, IIRC.
Color off
Grainy image
Zoom malfunction
Compass off by X degrees
Eye locked in position