No Mike, I had only cleaned the parts of the mechanism, I hadn't attached it to the machine as I was perplexed about the spring. Thanks Janey, I had completely forgotten that I had that pdf downloaded in my files it's been so long since I got my treadle and 99s.

Once I saw it in the pdf I nutted out how I thought it should fit and it was then oh so nice to have your explanation confirm it. Yay! Errrrrr....springs in the bobbin winders of the 99s'....oh yeah...lookey...so there are.....don't remember having to replace them......don't remember getting them out and cleaning them either...oops!
By the way Mike, do you remember helping me with that bobbin problem with the treadle? She's still sewing beautifully with her one and only original bobbin!!!