I've read many posts on this common problem and haven't solved my problem. The cog gear under the handle is in the 12 o'clock position and allows me to turn the handle from 6:00 to 9:00 (r to l), the hottest setting. I changed the position of the cog gear many times and anything other than 12:00 limits the travel to positions where the water is even cooler. I can't get a setting closer to 7:00 which might increase the temperature. What am I doing wrong?

The temperature of the hot shower water is way too cool while the sink (5' away) will nearly burn me. All other hot outlets in the house are satisfactory.

Thanks in advance for advice.

Has this always been an issue or is it an increasing issue over time? Putting the cogs at 12 is the best you can do. If the problem is getting worse perhaps a new positemp cartridge is worth a try.