What these instructions do is help you calibrate the knob and valve. The plastic knob has the hard stops, not the valve, so essentially what you are doing is adjusting the valve either hotter or colder within the range. You do this in 1/4 turn increments, to a max of 1/2 turn total. Adjust by 1/4 turn, then test your system for the correct temperature. If not quite enough, adjust another 1/4 turn. This should get you were it needs to be.
Slightly simpler instructions: 1. Turn the knob all they way to +, it's hottest setting. Yes, adjust it until it stops. 2. Loosen the screw on the knob, but not all the way. You want to loosen it just enough so you can pull the knob up off of the valve splines (so it disengages from the valve) 3. Turn the knob toward the -, about 1/4 turn. 4. Re-seat the knob onto the valve spline and tighten the screw. 5. Turn the knob all they way to +, until it stops.
Test your water and see if it fixes your temperature. If not, repeat the above. Hopefully this clarifies it a bit.
For the record, here is a photo of the mixing valve warning with the 2021 models and the 2021 320 TaB Owner’s Manual mention of the mixing valve. Sounds like there is a hard copy of the instructions in a new owner’s packet.
If you can, have your service dept. jump the thermal fuse on the circuit board, and see if it fires up. Those things have a limited lifespan, and are an easy fix, if you know how to solder. Since it's a thermal fuse, you have to use a heat sink or you'll keep blowing the fuse while soldering, so order a bunch, they're like a $1 a piece. I ordered 10 and we only blew one while putting it in. I now carry a jumper with alligator clips for emergency use.
Here's the original thread, hopefully this is the problem for you:
We park our t@b in our tiny backyard. It was snowing in May, 2016, when we brought it home. The boys were 9 & 10 then. We had a "movie night", tested the alde, and popped corn in the oh, so necessary small micrwave that has traveled all 35,000 to 40,000 miles we now have on the trailer. Glorious memories. As is now our usual, the t@b was fabulous, flawless and kept the outside elements away. Second best decision in our lives was the t@b. Best decision was to raise our grand nephews for nearly 13 years from the ages of 1 & 2 to the almost independent ages of 13 & 14. We still have the t@b and are blessed to have the memories of all our journeys and adventures as a family of 4 in it. Hooray for yard and driveway camping!
I found a pattern I liked and conned my mom into making mine. I might not have ever had them if I had not stumbled across this pattern. One down, one to go.
Standard Pickup Truck rear box. I think it's 60 inches on top. I got some aluminum "L" bracket from Lowes over the length of the box. Bolted the box to one side of the L, then bolted the L to the trailer tongue. You will drill holes in the SIDES of the tongue NOT the top. I used 3 stainless bolts with washers and nylon bushing nuts on each side.