I've had a Park PFP-6 pump for about two years, and while I've been disappointed with the quality of the product, I've been extremely impressed with the company's customer service.
After a year or so of using the pump on a pretty inconsistent basis, the base began to leak badly. The tool became unusable for anything above 30 lbs.
According to a Park service rep, the hot air which develops in the process of pumping had melted a hole through the composite base. He suggested that in the future I should run cool, unpressurized air through the pump between tires to cool the pump down.
The rep. couldn't have been more helpful. He sent me all the replacement parts for free, and didn't even charge for shipping.
Unfortunately, the pump still didn't last long after being rebuilt. Now, it's a struggle just to get 100 lbs. into my tires. Not sure if I'll bother trying to fix it again.