Those "plugs" used to made from epoxy. It is part of the "e" oiling system. It keeps the bar oil from running freely off the heel of the bar and make a sort of pool for it so the drive links scoop it up. The epoxy would wear quickly to the depth of the bottom of the drive links.
Bar measures 42 1/2" front of bar mount slot to front of bar mount slot
.063 gauge
.404 chain
Mount has lots of holes, I believe it is intended to fit multiple mounts?
I have attached a pic with the numbers stamped on the bar. Perhaps someone can translate them?
I have an older one that is a separate tool. Google turns up that the file holder and setting gauge are now available as one unit. Hopefully the pic works. The setting part is at the top of the pic.
Correct. Also, and maybe just as important, you need to have a setting tool. This bends the teeth outward to add "set" to the blade. Without the correct set it can be razor sharp and not cut.