Couple thing you might try.
First remove all loads on the gen when first starting. (and before killing the gen)
Start it up cold and then kill it before it gets warmed up and go for a re-start. Only let it run for 60-90 seconds) You are mainly checking to see if maybe the hard re-start is not all heat/hot related.
On gens engines when they are not running the governor has the throttle held at wide open. Tie the governor/carb at idle and try a re-start)
Also see if the engine idles good. This is to see if the low jet area on the carb is OK. (It's possible that it runs ok at 3600 rpm but won't idle smooth. (low jet carb issue adding to the hard start issue when hot)
You say the compression is 70. That seems low to me is concerning.
I've never checked the compression on a HM100 but I do know that normally they are very hard to pull through using a rope crank and they also want to kick back if they are not brought up on compression slowly and then pull through. I never could sense that they had a compression release.
(and even harder to hand crank in cold weather for a re-start) Hard manual cranking is main reason why I was doing converts to electric start.
Even with electric start I had to use a very good lawn tractor battery rated for around 250CCA due to the compression.