i didnt need to hit it with anything. all i did was press down on it and you will hear a click or two then let up on it really slow and your keepers and seat(or watever its called)should be stuck to the magnet. the tool comes in three pieces, the handle part with the magnet is the remover and the piece that is black is the installer there is also a small round hollow piece your suppose to put your keepers into when installing, i didnt use that because it didnt work right i think it may be too deep. now when you are installing the seat and keepers, what i did was set the keepers in the seat the same way they came out, the installer part of the tool slides in the remover/magnetic part. i just set the seat and keeper on the spring then lined the installer tip of the tool with the center of the seat where the keepers sit, and press down really hard(now you could hit it with a hammer or something but i didnt because i was afaid of losing a keeper since they are so damn small lol). when you press down hard you may hear a click or two. remember let up on the tool very slow because if the keepers are not right they could fling somewhere an that wouldnt be good. now let say you let up on the tool and one keeper is set but the other is half way set then repeat the process and remove it again then try to install it again. it sounds like a pita, but its really not that bad.
also i recommend safety glass because if the keeper dont seat properly and is half way out due to the tension on the spring it could fly out and put an eye out. but of course that up to you.
good luck and i hope i helped.