Thanks, I picked up a new gun style spray wand today for it at TSC, along with new tip strainers and tip holder nuts. The old ones were rusty steel, new ones are brass. Couldn't find wand rebuild kit through JD, nor EBay.
Here's a pic of it with the new spray gun, gauge, isolator.
Boom shutoff "T handle" ball valve purchased from an online plumbing supply house. U bolt connects the original shutoff handle extension to new valve handle:
New spray gun and hose from TSC:
New TeeJet type brass nuts replace the old rusty steel nuts on the boom. Strange that TeeJet nuts and nozzles fit but not the strainer screens: