While rewiring my 31 sport coupe head lamps, I ordered new lense gaskets.  What I received were much thicker than the original and did not work when assembling the ring etc.  After finding the correct gasket thickness everything went together just fine.  Good luck.

@honeycomb I'm not familiar with the '29 in particular. If you could post some pictures of the housing/lens/retainer and how the clamping system works I may be able to help. Working from your description, it sounds like you have the clinching type of retainer (bezel) where there's a screw that runs parallel to the bezel that, when tightened, pulls the bezel ends together. This type of bezel has a lip on one edge that fits in a groove in the housing, holding the lens/bezel assembly in place while pulling the bezel lip into the groove on the housing, holding everything securely in place. It can be a bit of a dance getting everything to line up and the bezel clamped securely. If the gasket is too thick it can prevent the bezel from closing enough to clamp the assembly in place. Of course this is dependent on the type of clamping system your car has. Again, pictures would be a big help. Show as much detail as you can.