E36 cab door issues

Hi. The door handles on my e36 cab are getting very hard to operate. An excessive amount of force is needed to open from the inside. This seems to be getting worse on both sides. When the door is already open it seems fine. I have removed the door cards but can see nothing obvious. The drivers door has now begun to refuse to open from the outside on some occasions. I have also noticed that if the window is down the handle on the inside operates easier.
Any ideas? What should i be looking for? any help would be appreciated

Do your windows drop a fraction when you open the door?

They're supposed to drop a fraction, to double check just push the little black button on the door striker on the car itself with the door open and see will they move.

Possibly door strikers as they're very common to go.

i had same problem on mine and the door mechanism snapped completely and ended up fitting a new handle,