Pedal keeps sticking after a few weeks, is this fixable?

[primitivoconner]

We bought a waste bin with pedal 68l for our clinic corridor about a month ago and the pedal has already started sticking halfway down, so the lid stays open unless you nudge it shut with your hand, which defeats the entire point of a hands free bin. Nobody is stomping on it, and I have checked underneath and there is nothing jamming the mechanism that I can see. Maybe dust is getting into the hinge, or the spring is already tired. Is this something you can lubricate or adjust yourself, or does it mean the mechanism is basically done. I am reluctant to go back to the supplier if it is a five minute fix, but I also do not want to void anything or make it worse by poking around. Has anyone had this problem and solved it, because if it is going to keep happening every month then a pedal bin is clearly the wrong choice for us.