I have an 8-yr-old Honda HRB215SDA (self-propelled). Recently, I noticed that the I would lose the transimission in the middle of the mowing. If I stop the engine and restar again, the transmission would be back, and then it would gradually disappear. On inspection, the clutch cable seemed to be loose, and the clutch cable lever seemed to be sluggish.

I tried to adjust the clutch cable by tighten the cable ajuster, but it didn't fix the problem.

Note that when I start the engine, I would still have my transmission. It would only disappear later.

Any suggestions? Thank you in advance.