Don't have that model lathe or control, but I can tell you how it works on our 42s with 18T and OT controls.
M84 brings tailstock in. M85 returns it. BUT the final position has to be set before using this command. There is a knurled knob on the bottom of the tailstock. Loosen it and move it back as far as it will go. (Away from the spindle.) This allows the tailstock to advance slowly.
Hold the Rapid Transverse in and press the left arrow key for the tailstock. It should advance at a slow rate. Use the feedhold located between the 2 arrows to stop the tailstock in the position where you want it to rapid to before feeding into the part.
Loosen the knurled knob and bring it towards the spindle until you feel it go over a bump. Sorry, not very technical, but I don't know how else to explain it at the moment. Then take it back over this bump and lock it down.
Press the tailstock return arrow to send it home. Tailstock is suppose to be set. Never worked for me. Hold the Rapid Transverse key and press the left arrow again. Hold onto your drawers. Now the tailstock will rapid up and start feeding in. I've always had to adjust the knob a couple more times to get it rapiding to the desired position before feeding. The first adjustment always has it stopping too soon. Sometimes the tailstock won't reach the part before coming to a stop.