W123 door latch

[mark82]

My door is becoming unfit to close. It sometimes take 4-5 slams, as hard as physically able, to close.

I found an old thread somewhere that claimed that if you look under the striker for a small plastic nub, and it is missing, the door will be difficult to close. One fix was to install a small screw in the resulting hole where the missing nub was. Another claimed you could buy replacement nubs on ebay, but as usual there was no specific link.

Now for the problem; three strikers are missing the nubs and they close fine. The only door with the nub intact, in fact the entire striker appears to be a new replacement, is the drivers door which wont close.

So do I replace the seemingly new striker or does the situation indicate some other cause?

Thanks