Can you just buy parts for these or do you have to buy the whole control. There is an older lady down the road, her husband passed away a few years back and she is going to have trouble paying for oil. She has an old Tarm 404 boiler and her daughter is going to move in with her to keep the boiler fed. Everything is there and ready to go except for the chain and the rod the chain connects too. Can I buy these two things or do I have to buy a new samson controller? Or can I make one? Thanks for any help. Brian