Mercrusier 228 with T.R. outdrive

Hi all I have a 1978 carver mariner with a mercrusier 228 engine and a t r drive , now when the drive is in reverse and i shift to neutral the boat remains in reverse to get it into neutral i must shift past neutral into forward and then back to neutral . this has made for a lot of fun while docking. Now i am aware that this drive has a electronic shift actuater and i think this is where the problen lies , I have search all over the net and various mercrusier sights and have found that the part number for the actuaterhas been superseeded several times and as i follow the numbers they always end with the part being obsolete is there a compatable replacement for this part , what do other boaters do, or is there a place i can get it