Nice write up and pics. I've rebuilt a few of these, too. Have one on the bench today as a matter of fact needing a top end (of course).
Got a NWP from DDave and was pleasantly surprised at the quality. Will need some very minor grinding to suit me a little better, but that's just me. I also usually do a vac/pressure test on the case and cylinder assembly (with the intake bulkhead in place) before committing to complete reassembly of the saw...., just because. Takes an extra 10 minutes and makes you feel a little more confident bolting the rest of it back together knowing everything is tight.
Two easy mistakes can be made when replacing a top end on these. The first is pinching the impulse grommet while reassembling the intake bulkhead (partition) to the cylinder. As noted above, it's easiest to have the grommet in place in the cylinder and the intake sleeve on the bulkhead for things to go together easily..., starting at an angle with the impulse tube going into the grommet first and rocking the bulkhead upward to work the intake sleeve onto the intake flange of the cylinder. Attempting to push the bulkhead straight into place has a high probability of not making the desired connection between the impulse tube and grommet.
The second mistake is hamfisting or cross-threading the carb bolts into the bulkhead threads causing a major air leak. Easy fix is heli-coils and some long 5mm cap screws or salvaged Stihl carb studs pressed in from the back. I've also seen ground down t-nuts used from the back with long cap screws. The one thing that won't work as a longterm solution is trying to use plastic weld or melt the plastic to re-thread the partition with the self tapping screws. It was a bad idea to begin with. Trying to re-create it after it already failed is a worse one!
Anyway, love these little saws. Great saw for a first-timer's rebuild. Great firewood saws. A gazillion of em out there. Inexpensive parts are everywhere. A guy who knows what he's doing can salvage a basket case 55 in a couple hours as detailed here and save a customer a lot of money at the same time. Plus they're great runners and tough as nails.
These have all found new homes and I have four more around here somewhere besides the one on the bench. Always seem to find em and bring em home with intentions of rebuilding em to live another day. Usually do.
