1992 Honda Accord Frequently Doesn't Go Into Reverse

Transmission problem
1992 Honda Accord 4 cyl Automatic 135000 miles

My car won't go into reverse, most of the times when it's been sitting for a few hours. In order to get it into reverse I try to shift between all the gears, or press down on the gas in neutral but many times I just have to finally put it into reverse and wait for it to pop into gear which most of the times happens within a minute or so. When it DOES finally go into gear it's usually with a jolt. I just had the transmission flushed which stopped the problem for about two days but now it's back. This problem does not occur with any other gears, only in reverse.