Although my M1028 had only 12,338 miles when I purchased it, the truck spent its entire life mostly parked on a National Guard base in Arizona. After Dependable Auto Shippers delivered it to me in Kentucky, and after a thorough inspection and evaluation, it was obvious that the Arizona heat had fried all rubber, and I assumed the rubber seals in the IP were also suspect. So as part of my frame-up rebuild/restoration, I decided to have my IP rebuilt. I contacted Cincinnati Diesel Injection and they would not commit to an exact price, because they said they wouldn't know what all would need to be replaced until they inspected my unit. I explained to them that I did not want an exchange, but instead I wanted MY IP rebuilt. In a leap of faith, I used my engraving tool to inscribe my name on the housing, boxed the unit and shipped it to Cincinnati. About a week later I got a call from the technician assigned to my pump. He said the pump appeared to be in excellent condition, except the rubber seals were deteriorated. Since it was important to me to have peace of mind of a reliable pump, I informed him that I wanted to completely rebuild the unit. We agreed on a price of $550 to completely rebuild my original pump, and this included a new check valve on top of the unit. I gave him my credit card info, and a couple weeks later, UPS delivered my rebuilt pump. I also purchased new Bosch injectors and glow plugs from Cincinnati, and these were included in the shipment. I had already found and purchased an NOS high-idle switch, but before re-installing the unit I decided to paint the bracket 383 Green. I also installed an NOS vacuum advance module on the side of the pump (this was difficult to find). I then installed all parts on the engine, including an NOS open-plane manifold. After bleeding the system the truck fired right up and run perfectly. It now cranks instantly after normal glow plug cycling, and runs strong and smooth down the road. My recommendation - spend the money to have your pump completely rebuilt, and if your budget can stand it, go ahead and install new injectors and glow plugs. Make sure all connections are tight and all air is removed through proper bleeding.
Hope this helps.