John Deere L130 lawn mower Pto not engaging in forward position?

My blades will only engage when I'm going in reverse with the RIO button being held down not simply pushing it once to go backwards in reverse,but nothing in forward.Aside from not being able to cut my lawn everything else has worked fine for 3 years.Assumed it was a safety switch,but there are too many to try and figure out.Sending it to the dealer will cost too much with pick-up and delivery,for a retiree.knowing full well it's just a switch or relay.Any one know of the solution?Would be GREATLY APPRECIATED!I could just order the part and put it on myself.Thanks!