Try gun shops, on line auctions, egunparts, pawn shops and gun shows.
It is located on the left side. Called a Magazine Cutoff, It allows you to keep the magazine tube loaded when you empty the shell in the chamber. Flip the cutoff lever and then open the breach bolt. The chamber will empty, but no other shell will be released to the carrier.
A Savage 745 is essentially the same design as the Browning Auto-5 and looks a lot like it. The big visible difference between the two is that the 745 does not have the magazine cutoff lever on the left side of the receiver like the Auto-5.
Autos and pumps, on the receiver. Over/Unders are undr the breech locking lever
Browning Lever Rifle
Your browning lever action 22 was made in 1976.
It blocks off the magazine to allow the shooter to change the shell in the chamber without needing to empty the magazine or manipulate the lifter. The "classic" use was changing from a duck load to a goose load.
Belgium
"BLR" = Browning Lever Rifle It is lever operated
no
NAFAIK.
You do not want to try this. Find a qualifed Browning gunsmith.
They are not hard to find or buy as I bought lots of Lever actions