Hi Jen,
is your engine a full circle crank web one?

Many of the PAW DS's were and can be significantly improved by grinding the cheeks off them or if you want to really address this PAW offers a piston lightening service as well.

Beyond that the vibration could simply be the harsher rapid onset ignition combined with a model really designed for a smoother running glow engine.
What size engine are you using and what size engine bearers? Most PAWS I wouldn't go under 1/2" square hardwood that run back to the wings high point at least or a radial mounted model with extra attention from F1 back to the same high point.

Also try some ignition improver, this will lower the compression needed and should give a slightly smoother run.

Cheers.