Sounds like she could be wearing out.I had one not so long ago did exactly what your is doing.What I found was due to the heat of the engine it was evaporating the fuel in the carby and couldn't and wouldn't run when hot.I also had another with similar problems but it had very worn rings.
One way it could solve the problem was a part Victa made for them was this.
[Linked Image]
It pulls the carby any from the engine as well as putting a little barrier between them.I'm not saying it will fix the problem but it did help in my case.

Here for a good time,not a long time.