can a 7x12" import bandsaw use a 1/2" wide blade?

If its the horizontal cutoff type, most likely no...there is a lip that the blades rides against that sets the blades width, with the set of the teeth just barely overhanging the opposite edge , and using a narrower blade would flatten the set on the one side of the blade.

If its a vertical type (7 x 12?_) most vertical types can use various width blades.......but yours sounds like a Horiz>===It came with a 3/4"

REMEMBER: "This is worth repeating for benefit of al newbies! Jo Ann asked Dr. Solo to remind people that while she has retired from selling GF (and sold the business to Ken Fischer