transmission won't engage when you push the button on john deer 155c automatic
because it needs a 1600 vee dub engine in it to make it go faster to have lawn mower races
The STX-38 should have an electric clutch for the mower deck. The switch to engage it is on the right rear fender. It is a toggle switch. You will have to pull up on the switch and forward to engage the blades.
The manual pto is the switch used to engage the mower deck.
The belt is too loose. Replace it or adjust the idler.
check the front and back belt pulleys and if the elt is on the right side of the engager.
on the mower deck
look for the engage switch that has a picture of blades
john deere LT155 38inch cut mower deck
you were no help
38'' deck
Measure the width of the deck with a tape measure.
mower manuls are at this link http://manuals.mtdproducts.com/mtd/DocGetter?doc=769-00533.pdf