How far off from straight is it? In which direction is it out of alignment?

If its off in pitch, you should carefully remove the stab, and remount it. There's not much room for error in that direction. Fortunately, the GWS glue will peel free from the "egg carton" foam if you are careful. It'll fly with the stab off by up to 5 deg ether way... elevator can overcome it. The problem is that the plane will pitch up and down with speed changes, and that can get really bad when you go dead-stick.

If its off in yaw, no biggie up to 10 deg, or when the rudder hits the elevator, whichever is first. It'll give little roll couplng to the elevator.

If its off in roll, again up to 10 deg is not a big deal and then it would give a yaw coupling (which on that plane would roll it too...)

Generally... the stab has to be WAY off before they won't fly in a controllable manner.