Chainsaw Repair

I was given a husky 435 and as I was putting the clutch cover back on the mounting stud for the bar went back into the saw case and is no longer sticking out.
Anyone know how to fix this and why the stud would disappear? How does  it attach to the case? I have owned a lot of saws over the years can't recall this problem ever happening.
Thank you

I use a telescoping magnet to help me guide bar studs back into case holes.  From outside the bar oil tank cap area.

Also on some saws like the 350 series, theres a metal channel support (I call it) that helps distribute the pressure against the case that is between the stud and case.   If your saw has it, then it should still be in there providing the other stud hasn't fallen out prior.   I use a long locking 8" pair of forceps to re-position these.   I had a 435 once, but never had any problems with it, and was a good saw for light limbing.  Hope this helps ya.