I have a Moen single handle tub/shower similar to this model:
The lever does not need to be pushed in or pulled out.. just rotated for water flow. As soon as the pear shaped knob is pointed 10-15 degrees just right from straight up, the water output from the spout turns to 25% of acceptable. Pulling the pin on the spout to activate the shower head takes a while for water to come out and is also weak pressure.
Bathroom plumbing is on an interior wall with access if needed by cutting drywall from other rooms.
Is this fixable by a DIY'er? or do I need to hire a plumber?