You do need the new computer board along with a hydraflex button on the counsel. I believe the combines were first updated with the new style board in 2002. I don't think the new board has anything to do with the reel up\down.
I think it should fix the problem, the reel lift and dydraflex are run off the same line with a elctrohydralic valve on the right hand side of the head under the removable plastic shield, with a four wire plug on it. One line splits off and goes to the reel lift and the other goes to the hydraflex. I found this out while I was adapting the 620 hydraflex to my 7720, It maybe a little unconventional, but the head works wonderful compared to the 920 head that I had on it.
I am placing a 630F on a 2000 9650. I am told I need a new mother board to run the hydraflex. After hooking it up I have found that the reel will not go up and down will this new mother board fix this problem as well??