I have a murray riding lawnmower model 42828x8A when I set to engage to travel he sounds like it is not engaging fully and will not move without me helping it. It will however go in reverse and travel.

Could be your tension adjustment needs to be tightened on the belt between the transmission and the engine pulley. Have someone operate the cltch/brake and watch how the rods and pulleys move. You should see the tensioner pulley press on the belt, the arm that pulley is mounted on is adjustable.

Hi,
A worn belt, bad idle or shift-on-the-go out of adjustment. Parts breakdown at:http://www.outdoordistributors.com/pdf/Murray/MURRAY-MODEL-42828X8A-LAWN-TRACTOR-(1996)-PARTS-LIST.pdf
Peace,
Clarke