Can't Start Masport Maxicatch-400 with Briggs+Stratton Quattro 40 Eng?

As well as seeing that the governor springs don't seem to be doing anything, i.e no movement when throttle cable in fast or slow position, springs 'loose', I can't get the thing started. There is fuel in , a nearly new spark plug, and was in shop last season for this problem and has started successfully only after getting it back once only. Since getting the machine 4 + years ago or so it has always been plagued with erratic starting. - Any suggestions gratefully welcomed.