I'd be cautious of using PU in any engine mounting due to my
experience with a previous Mazda.
One of the mountings was badly broken, and I 'repaired' it with epoxy
PU.
It was a massive failure as vibration went right through the car.
It was undrivable. I tried removing a large portion I'd put in but there
was virtually no improvement.
Perhaps ask Mark for some feedback from other users.
Peter is on the money with the engine mount. If it's dry and visibly supporting, i.e. the
wedge shape is up, it's ok. As he says, the others don't suffer generally.
N.