I'm not so sure about previous answers.
I did not add a mechanism for the weapons to be damaged on WMIK. There are no hitpoints or hitpoint classes in the weapon turrets.

In single player (non-@ace3), with hitpoint debug switched on (a 3CB dev tool), and setting the vehicle to 85% damaged, I'm still able to rotate the HMG freely without issue.

To be able to troubleshoot, we need a repeatable test that can demonstrate the problem. Report back here with a method (list all mods loaded and a step-by-step description of how to repeat the bug), if you're able to find it.