I totally agree. With the carpet in it can be a bit of a wrestling match to get the seat into the catches on the floor. Also, the original catches require three motions- You slide them in, push the seat down, and then slide it back to lock it in place.
The other possibility is that you have a lower seat from a different A-body, so maybe it looks close but won’t go. Like for example, if you have a ‘73 seat bottom it may not have the corners clearances for the seat belt retractors that the later cars had. Pictures would help lots.
