Hi,
I have had this before with a road bike, I pulled the forks apart, so I could roll the stanchions on a flat surfave, I used a pane of glass and looked for a gap appearing along it's lenght as I wolled it, much the same as you would do with a snooker que to see if was bent on a snooker table, the forks are easy enough to pull apart, so don't be scared if you have not done it before post a question on here for more help with that.
I am not sure if the bike you have has one fork for the damping and the other for the spring as you do not mention the year (and I am really a Montesa man.... no spitting please), in which case, one would be easy to compress (the damping leg) and the other would be hard to compress as it has the spring in it so don't be fooled into thinking the legs are bent because of the ease of movement.
I would pop the forks back into the clamps but don't tighten them, don't refit the mudguard stay and see if the axle lines up correctly, you may need to compres one leg to get them lined up vertically, however you need to be more worried about the horizontal alignment, this will give you an idea if they are well bent, as the axle will be quite a way out.
also, look for any signs of visual damage on the stacnchions, they tend to crease if you have given them a real whack...
I hope this helps.
Dave