Hi All-- Looks like quite the expert group here. I hope you can help.

I have a submersible pump (not sure how deep but deep) and a culligan water system.Recently, water has intermittently stopped -- especially in heavy demand eg. washing machine and sink on at same time. Pressure gauge in one of the tanks near the culligan stuff seems to bounce between 0 and 40. Plumber says I need a new pump and quoted ~$2,000 and a friend says it might just need air bled out of the tank. Pump is 10 yrs old if that matters. What do you all think? Thx for your help