I was taking out the wet end for a cleaning and found that the magnet and screw is beginning to rust. There is also a large grey colored blister protruding from the magnet. I've only had my vortech running for a little over 3 months. I thought these magnets would last 18-24 months before it needs to be replaced? I've already sent it in for warranty work in January (purchased the pump in December). Do I have to send it in again or can you guys just send me a replacement magnet and I install it myself?