I have the same problem, I stripped the carbs down on my CB550F as I thought the main jet o rings needed replacing, they did, but on the second carb I found the leaf spring in two parts.
I have tried a number of breakers with no luck, can anyone help?
If you have a spare leaf spring (it retains the main jet) I would be most grateful, happy to pay postage and a fair price, I am in the UK.
regards