I have a roughly 8 year old Honda Harmony (2 speed) self propelled mower.
Once, if not twice per season, the mower begins slipping while engaged.
This will cause the mower to slow, then catch, then slow, than catch.
Releasing the clutch and re-engaging helps to re-engage most of the time. I
have tried to tighten the cable myself after paying the repair shop several
times. Nothing seems to last longer than 20 - 25 mowings (1/3 acre) before
the problem appears again.

Any suggestions for stabilizing or fixing this? Perhaps hints to tightening
the cable properly would help.