When reinstalling the standard birdcage f.h. is it also necessary to replace the washer? The slots will no longer line up at the top?
Thanks.

If your using the crush washer (coned) yes.

The peened washer, then it should be the correct thichness as is, unless you changed FS's. If this is the case then you will need to remove a layer or two to get to the correct index.

With a new cruch washer, spin the FS by hand until it is snug against the washer, then slowly turn the FS to the correct index. The washer is self torqueing, so stop once you have turned the FS to index, don't try to bottom out the washer.

I guess I must have the "crush" type as it definately has a cone type of appearance. It is the stock one that came with the BM. upper. Thanks for clearing that up for me. I could not figure out why the heck it wouldnt line up and it was driving me crazy.