I have a Kitchenaid stand mixer. Purchased early this century. Not used a lot. Goes in spurts. It has developed a glitch that baffles me. Anyone have this problem, or a solution?

When trying to put on the flat beater that is covered in white, the beater becomes caught. It won't turn so the knob (don't know what it's called) won't go into the slot. Hubby has to manhandle it off, because he can't get it to budge, either. I have 2 of those beaters. Yesterday, after he pulled off the first one, I thought it'd be okay with the second one. It also became stuck. Again, had to be manhandled off.

This is the second baking day I've had this problem. If my husband weren't home, I'd be out of baking luck, because I can't pull it off when it refuses to move.

I'm wondering if the spring that moves when the beater is inserted and removed could be broken. But, there was a long time between the first instance of this and yesterday, when I used the mixer with no problem.

I also don't know if the spring is even replaceable. And blaming the spring is just a guess. Anyone care to hazard a guess or have knowledge? Thanks.