So after solving the starter cord knot interference problem, and the carb problem, that left the missing chainbrake issue. Fortunately I had a spare 55R carcass with a donor brake, so I set to work on what I thought would be a simple parts swap. Took the 55R brake apart and found one arm of the flat spring was broken off, so ordered that. I felt ambitious today, watched a couple YouTube videos for ideas about assembling the parts in the 154 clutch cover. Unfortunately they were kinda vague about exactly how the V spring fit inside the handle, so I struggled with that until I found that putting the pin with the snap ring in first, before fitting the handle to the cover, helped. That left the round spring install, and it looked like a 55 spring might be longer than a 154 one. No way that spring would fit in the recess, unless the brake was in the “on” position. That left the dreaded brake reset problem, which thanks guys a thread on this site solved. Got a 55 carcass and pulled the clutch off, bolted the cover on the bar studs and zip…pulled the brake to “off”. Now it’s all bolted back together and ready to throw some chips, and compare to my other mid 50cc saws.