you might be able to get all 4 screws out of the cover and lightly break it loose from the stock gasket but alas no worries bro, a $5 tube a silicone sealant will seal it up better than stock anyway
(make sure its gas/oil resistant on the package tho)
the seal you might be able to push back in place as long as the magneto hasnt torn it up but better to leave it alone if its not falling out or non exisitent.
if you remove your magneto, be careful you dont loose the woodruf (timing) key when you pull it off. put a tarp down or a t shirt or something to catch it in case!