280 SL door check noise

[desert]

I had a door check installed on my 85 280SL by a local "European" shop that has recommendations on this forum. They did it for a fair price and seemed to know what they were doing but a couple of days later when I open or close the door it sounds like a spring expanding and contracting, something like an old screen door that has a spring on it. They are going to check out the problem but before I take it down to them does anyone have any ideas what could be causing this sound? I always like to have an idea what is causing a problem before talking to the shop boss....Thanks, Desert