Hey guys Im kinda new to the GA world and I'm looking for a little advice/help to save some pennies. We recently just purchased a 1969 PA-28-180D Cherokee. It runs great but, like anything this old, it has it's problems. One of the first things I noticed is the hobbs meter not working correctly, it only read 3 hours on a 5.5 hour flight back to Texas.I have to go off the tach and im basically shorting myself time because of this. I know flight schools have them tied into the Battery to start cycling when the battery is turned on, Im not necessarily concerned about doing that as I crank the engine 20 seconds after flipping the master. My question is, Is there an oil pressure switch behind the hobbs that needs replaced with the Hobbs? My father is a 35 year A/P IA for American Airlines so any maintenance can be done by him, he just isn't proficient in GA airplanes like he thought. Any replies would be greatly appreciated.