The first thing I'd like to state is that the HF air compressor stinks! Don't buy it. It is not direct drive as most are; it has this small belt that drives an eccentric sheave (or pulley) to which the piston is mounted. And this friggin belt will rip on you easily! After purchase, the belt that originally came with my HF compressor lasted all of 1.5 weeks! I couldn't believe that. But yeah, that was the case.At the center of the issue is the design. It's horrendous. There is no adjustment in the form of a tensioner or even a slot. Nothing. Just two sheaves that you have to wrestle a replacement belt around. I tried to loosen the driven shaft but the retaining bolts (which are small) stripped. And so there was nothing left but to try to install one of these belts by "force".That isn't easy. These belts are a TIGHT AS HECK fit. I struggled with this for approximately 4 or 5 hours, trying different things such as the loosening of the driven shaft, forcing the belt on, etc. In the end, the only way that I was successful was to put the belt on both the drive sheave (pulley) from the electric motor and the driven sheave (pulley) on the top side. I then used my right hand to hold the belt onto the drive sheave and the outside of my left hand to hold the belt onto the top side of the driven sheave. Then with both fingers I was able to apply enough pressure to start the belt around the outside of the driven sheave. I then rocked the two sheaves back and forth (rotated them left and right via pressure with each hand) while continuing to apply pressure with my thumbs against the bottom side of the belt. Between the left and right rotation of the sheaves and the pressure, the belt eventually made it onto the bottom of the driven sheave.To be clear, at this point the belt was only on the sheaves by a couple of ribs. Thus some work remains. Being careful not to do anything to cause the belt to slip off (which it will READILY do, especially off of the small drive sheave) I rotated both sheaves fully (not rocking them back and forth any longer) while applying pressure to the belt on each sheave. This caused the belt to jump ribs and become fully seated onto both sheaves.Whew! Lemme tell ya, that was difficult. And how. That said, now that I developed a technique for how to complete the installation, I decided to write a review to share that procedure. The hope is that it will save someone else the agony that I endured. Good luck!And DON'T buy the HF compressor!