prolly one of your safety switches acting up or failed -- to troubleshoot, elect digram and VOM/test light would help.

Do all the blade pulleys and idlers on the mowing deck turn freely by hand?

A shot in the dark...make sure the battery is up to par.

Are you giving it enough throttle, is the engine warm enough?

The battery has absolutely nothing to do with it as its sole purpose is to start the engine

Unplug the PTO and try, that will immediately tell you if it's electrical as in a safety switch or mechanical as in binding pulleys, etc. If it dies with the pto unplugged you'll know it's electrical.

I have heard about shorted coils in the PTO which "could" drag down the voltage but that's a stretch I think.

Good luck,

Ev

Check that the Grass Catcher Viewing Lid i(if fitted) is firmly closed and properly locked. The engine will cut instantly, as soon at the blade on level is moved a fraction, if this lid is not firmly closed!

If not, around to ensure that all panels are secure, as there are sensors which kick in if they are not closed.