Moen Posi Temp shower valve adjustment question

I have a Moen posi temp shower valve, and the water just doesn't get hot enough anymore. The water temperature in the rest of the house is fine. I know that there is an adjustment that can be made, but my shower valve appears to be missing the key stop and temperature limit stop. I have two questions...1) Do I need to buy these parts and add them, and 2) will this help my problem?

I have attached a picture showing what my valve looks like once the handle and the black plastic handle mount have been removed.

The limiter is part number 106479. But with it missing, you should have the full range possible from your water supply, so I suspect you have a problem with the spool. Replace the positemp cartridge'