Anatomy of door striker.
First of all the first washer just slides off but the second...not so easily (it took lots of muscle and vise-grips.)
Secondly, the second washer butts up to a stop that is an integral part of the bolt.
Next, is the sleeve, (although it never turned any using the vise-grips there to unscrew the second washer.)
In the grooves on each end of the sleeve is an almost rubber like seals or something.
I can only wonder how on earth this striker bolt was made in the first place.
The nos striker bolt 210151274 is a much simpler piece but it definitely looks different and the 20151275 striker has a larger washer stop than original.