Very low pressure in the hot position probably dirty valve but how does this come apart?
Is this a new condition? Do you have a Aquahot unit?
I took one of these apart recently in a friends town-home. Home Depot sells a cheap puller that pulls the valve body straight out. Easy fix. Just buy a new cartridge and make sure that you use plenty of the supplied lube when putting it back.
Search Results for fawcett cartridge puller at The Home Depot (http://www.homedepot.com/s/fawcett%2520cartridge%2520puller?NCNI-5)
Keith
Started recently, we have no aquahot
all you do is pull cartridge out. If Moen take it to a wholesaler and they should give you a new one free. I have got them free and was told that there was a design error on them and Moen just swaps them. Done it twice here in Canada. Yes use lube too.
JohnH
Thank you all for the suggestions, called Moen support and they are shipping valve
Glad they are sending new one Hans and do not forget which way you took old out or you will reverse flow if wrong way in. When you have old one out check inside "tube" and make sure it is all clean, no bits of rubber from seal face or end valve left in there. You do not need puller (or should not)
JohnH
Update, had a wonderful Hot shower after much tinkering and tapping on the pipes. Waiting for a new Moen insert as well. Thank you Hans!!
When you have the valve out, turn on the pump to flush pipe just before valve. I did that on the one at my house and it flushed a few particles out.