I'll keep taking my meds and hope to pull through...
On a more serious note, I did wonder f I saw a roll-pin through the top sprocket in your first picture. Maybe it's an "improved" version if so?
Also, I have found 3 other things that seem to apply to all my sets, based on Bob Sobol's excellent work.
- The centre lines of the top and bottom shafts are not parallel. The top shaft's boss seems to have been angled down a little in the tower design. This causes the chain to always be pulling at an angle to the teeth, no matter how well you align top and bottom sprockets. Definitely a cause of constant hum/noise.
- The sprocket boss is too narrow on one side. This means the chain sticks out beyond it and rubs on the washers supplied. Definitely a cause of constant hum/noise. Bob S made some top-hat washers to create clearance - see his pics on Smugmug. I don't have his skills and equipment, so I use sleeves cut from brass tubing between the sprocket boss and washer.
- Some replacement sprockets are cast not machined, and have the mould halves mis-aligned so the teeth are too wide for the chain. I don't think you have this issue though.
Apart from that, it's a great drive system!
Cheers,
Pete
