First time doing this. Got pulley off impeller shaft, removing hex fasteners (10 and 2 o clock), have new pulley and key (the old key had fallen out, the entire assembly was wobbly).

The new key is the correct replacement part, but I'm having trouble inserting it into the depression in the shaft. (It fits snugly into the pulley hub OK)

Is it common to have to shave off the sides of the key slightly, with a fine grinder, say, to get it to fit into the depression? Then what, tap it in with a hammer? Thanks, guys. Gary