Hello Ben and all.
Yep, I had the same problem, and agree with all of the observations made by others for the 'fix'. Two really basic things (so basic I am embarrassed to mention them) also help, and offer peace of mind. First, I automatically ask any passenger to engage the safety lock on the door, and I keep it engaged whenever travelling alone. (I only do this in the Pagoda; I feel claustrophobic doing it in my other cars). Second, I always ask passengers to take care not to slam the car door when closing it (and I take the same care, of course). I found that this greatly increased the periods between which it became necessary te re-adjust the eye on the door frame: as the shim is original, it doesn't grab as well as it once did, and slamming the doors pushes back the eye a fraction each time. When I can work up the enthusiasm, new shims are on the to-do list.
Cheers,
kns.
1965 230SL, Manual
[1965 220SEb Coupe, Man.]