DMV, you aught to by your self a repair kit for this unit, it's a straight forward job to install the diaphragms and any springs you get with the kit, this unit did not come of another truck 25years ago did it. The thought being this will come in useful one day, I'm sure we have all done it at sometime or another.if that's the case then you may find that heavy ends have solidified in the honeycomb tracking as I call it, it's easy enough to clean out.

Regards Titus