As Star stated, few little info is available for these 40 year old units. The only suggestion I have is to try and locate a small engine bone yard within reason driving distance. If you are new to scrounging like this give them a call first. I’m lucky I’ve got one within 100 miles and have used him many times when the customer is willing to pay. We’ve become friends so I’m allowed to walk around his 20 acres looking for what I need, plus have a friend 5 miles away so always stop and see him. Great way to have an afternoon of peace and quiet. Saved more than one unit doing this.