Gontar

Hi. I've recently installed my Alldays & Onion 1cwt, I'm having trouble with the treadle, it's a bit stiff going down but can still forge with it, it's when it goes to return it doesn't want to without me aiding it. it has been sitting around for over a year and I've left the hammer running for over an hr to warm it up. Just wondering if it's a common thing or do I have to take it apart to fix. thanks Tom.