Small Engines (Lawn Mowers, etc.): Murray Riding Mower, nuetral, linkage

Question
Hi, I have the following:
MURRAY RIDING MOWER, 12 HP, 38" CUT, MODEL: #38623X5B, SERIAL: #283707 (B&S) ENGINE.
My question is.....
**When I want to go into reverse, for some reason, it keeps stopping on me. As if something is slipping. I have to keep messing with the shift handle/break pedal for it to continue. And if it does it still stops after a foot or so.
Plus when it is in nuetral, and I go to get off of the mower while its running, the gear will just kick in and the mower will just start going forwar. I don't know if this is all tied in together or not.
Please help me in telling me what you might think the problem is here?
It goes forward ok, just not backward right!!
I know that in 1999, I had a simular issue and a STARTER GEAR/REPAIR OF THE LINKAGE/ADJUSTMENT WAS MADE. Again.....would it be the same problem again?

Please, any help would be appreciated!!
**Finally,would I have to be an expert to fix this?
Thanks Much!!

Tom B.

Answer
TOM, TRYING TO DIAGNOSE AND ADVISE A REPAIR SUCH AS YOURS WITHOUT BEING ABLE TO HANDS ON THE MOWER WOULD BE LIKE TRYING TO PERFORM BY PASS SURGERY ON A LION WITH BLINFOLDS ON.  I DO THINK A LINLAGE IS OUT OF ADJUSTMENT WHICH ONE FOR IT IS I DON'T KNOW FOR SURE.
GOOD LUCK,
GEORGE