The first one had the rubber diaphragm in the pressure switch fail (~2-3 years). I came home from work and it was running (for HOURS?) and leaking out the pressure switch. I replaced the pressure switch with a GOOD "Square D" pressure switch and still use it.
The second one had the check valve fall off (due to corrosion, it's just cheap porous aluminum) where the check valve screws into the tank (threads broke flush with the steel fitting). I took the motor/compressor unit off and adapted it to an old propane tank with a new BRASS check valve & gave it to my father in law.
The third one I bought probably 7 years ago and it has been flawless. I use it almost every day.
There is a secret to these things:
When new, run the compressor at LEAST a couple hours worth of use with the cheap oil. before you drain the oil, run it LONG to get the oil good & hot and drain every drop out. Replace the old oil with GOOD oil with a tablespoon or so of STP oil treatment added. I have never had a motor or compressor fail of these three I have owned. Sometimes I run them for hours without a break.
cheap compressors are luck of the draw, some last some crap out pretty quick, good oil helps as well as keeping the moisture drained.
a Devillbliss Emglo or Webster cost many times more, if you need some air to occasionally change a tire or inflate something any compressor will do. if you want to sand blast or do much plasma cutting you need a serious compressor.
I highly recommend not buying compressors with plastic tubing connecting to the pressure switch, I've seen that nearly melt and come off, as it is I have a portable double tank compressor that has a plastic pressure regulator that's beginning to have leakage problems, but at least it has copper tubing going to the pressure switch. I also dislike the fact that it's such a high speed motor, just like generators, I'd rather my equipment ran at low RPM's. One other thing I need to mention is that I've seen more than a few Chinese motors have the centrfugal start winding switches go bad and you might as well change out the motor as to find parts to fix the switch. With almost everything being made in China and other third world nations, do they even make good electric motors in the USA any more? When I worked for the local school district as a maintenance person I used to get Baldor motors, one of the few brands that had grease zerks on the bearings, at that time they were one of the best motors I could get, but then most of the motors used in the schools were three phase and never had start windings.