hi.. I have a house built in the 60's with old black and white vinyl (?) tiles (1'x1') and I just can't get them clean... I have tried bleach, ammonia, pinesol, a scrubbing brush... occasionally I can lift a tiny bit of the surface dirt to see the tiles can be cleaned.. but have yet to be able to do the whole floor.. any suggestions of a product I could try? I live in Canada