I have never engaged the PTO on the H16.
Never engaged it - hmmm - What is the condition of the current PTO belts, brand new or old, frayed, and cracked?
Engaging the PTO puts a large sudden strain on the belts and they may break and flap around your engine compartment, making a huge noise and tearing out all the wiring. DAMHIKT.
(although if you searched for a thread "how to instantly remove all your wiring...)
Simple stuff - did you grease the PTO? Recently? Does it spin freely? Remove the plug wire, then crawl under and inspect and spin the PTO shaft by hand.
Now you can run the engine and test the PTO WITHOUT the blower. (Oh, yeah, hook up the plug wire) Start it up. The PTO should not spin if it is not engaged. If it does spin, then look in the manual how to adjust this. Gently engage it. Sounds good, no grinding? Engage - disengage - engage - disengage W00t! Shut down.
Check the blower.
Have you recently greased the u-joint connecting to the blower? Blower fittings? Turned the blower shaft by hand? OK, it's all good with no binding.
Now hook it up to the tractor. Wear gloves - there are lots of pinch points. Lots of band aid opportunities. I like mechanic's gloves and use them all the time on the tractor. Heavy SOB, ain't it?
Attachments should be operated at WOT, but some people reduce the rpms when engaging the PTO, then push it up to WOT. Supposedly it helps the belts last longer. I reduce RPMs engaging the rototiller, and it does emit less of an unearthly shriek when the belts slip and finally grab.
Do not engage the PTO slowly, it will not help. Don't slam it either. Just confidently engage it. Everything spins OK? Play with it a while, get a feel for driving with all that weight in the front. At least for me it was very different from a riding mower or a naked tractor. Up, down, engaged, not engaged, spin the chute control.
Play with it now because when you start chucking snow you really want to pay attention to where that grinder is pointed, you do not want to be distracted. You do not want a bush, your mailbox, or Rover sucked up and distributed 20 ft across the lawn.