i shift to reverse(when cold)it grinds.when op.temp normal(slips in and out) on 1996 Saturn SC2

all forward gears work very well. when it slips out of reverse (for maybe a quarter of a second) it recovers.this happens approx. every 6 or 8 feet of travel. i changed the filter...didn't help.

Asked by for the 1996 Saturn SC2