The coils on my 550 were OK apart from the HT leads which were old, stiff and wobbly (sort of like me) Having seen other posts where people dug out the old leads and attached new ones I thought I would do this on my milling machine. The main purpose was to allow the part of the coil to remain in place where the leads attach so the new leads would have maximun possible support. Machining out the old leads was reasonably easy the only comment was that the leads were all moulded in place at different depths and angles. Tinning the stubs of the old leads in preparation for soldering the new leads in place needed a good flux as the copper wire was not bright. The new leads 7mm in diameter were easy to push into position where after soldering a drop of thin super glue was allowed to capilary down the side of the leads to stop them from rotating. After that clean everything thoroughly and pot with an epoxy.
