Peter Burrows (Alphatech) makes an excellent replacement spring - easy install.
alphatech@carolina.55.com or call him at 704-293-5517

I have also gotten replacement Door stop springs from him as well as the nylon bushings for where the over-rider bars attach to the bumpers.

Pete Burrows from the now defunct website "alphatech" used to make and sell these. I have one from him and it works flawlessly. Maybe his email still works and he has some on hand:

Pete Burrows: alphatech@carolina.rr.com

If I remember right the rubber door stops were pointed which compressed when the door was closed but was supposed to be tough enough to help push the door open. This did not work for me. One thing that really works good is to make a bracket in the left top of the glove box door jamb just large enough to accept a push button door jamb on off switch. I can`t remember what switch I used but it is round and has a tough spring and is all metal. The diameter of the switch is 21 mm. Probably any good push button jamb switch would work. The small led strip lights in the roof of the glove box lights up the glove box real nice. The spring in the switch opens the door just fine. Really its worth the time. Larry

I don't think there was ever a spring-assist for the glovebox door on a 544.
Pretty sure it was always gravity-assist!

I suspect there may be some kind of alignment issue.