Check the slot with another card...it could be a small part of the card has broken off...never force a card into a slot...if it still won't click home...worse case scenario...use a flashlight and look into the gap of the card holder to see if the metal tongues are misaligned...If they are bent out if shape...then you can try Luton Cameras for spares....they usually supply for canon and Olympus but sometimes keep Minolta Sony bits or will direct you to another source...lastly go to eBay and see if you can source a spare and repair Sony Alpha...
I think most Minolta models use the same module for card slot holders.