That's low hours it should do 500+. I have a similar pump in my airflex and I changed the head but it had done 550 hrs and was still working well. I also use acidic rinse but do flush the pump with cold water at the end of each day. You wont really know what the problem is until it's stripped, but it would be worth having a spare head ready to go, you may be able to recondition the one you have and keep as a back up.