Years ago I lost the factory rock guard supports on my 79 Boler
. Mine didn't have the buttons and holes but a slide with a screw for different positions...Anyway I made my own with 1/2 and 3/4 inch CPVC plumbing pipe. The 1/2 slides inside the 3/4 and I have several holes to insert a 1/4 Brass bolt and wing nut at different positions.
I knotched the top of the 1/2 to fit the rim of rock guard and the bottom of the 3/4 to fit the latch lock on the bottom again a 1/4 bolt and wing nut on each end.
Hardest part of operation is lining up holes when adjusting.
Took me about 2 hours to do.
For God sake, do not drop a tarnished, brass wing nut on the ground at twilight...almost imposible to find