Hayter Harrier 48 problems

1  Recently my lawn mower started hunting which I tried cleaning the jet as mentioned in an earlier topic, but to no avail.  I tweaked the throttle and it runs reasonably OK when cutting although not when blade disengaged.  Any ideas please ?
2  Today I tried to start the beast but could not turn it over, too stiff !  I ended up engaging the blade and holding the 'deadmans handle', and it starts OK.  When I release the blade rotation, the engine cut outs out abruptly with a clunk. Clearly something is amiss but I'm not sure what !   Again, any advise would be appreciated.
Are the two related I wonder