i think zongshen china doesn't have strict quality control of their products thats why some units are ok some are not, or maybe the problem lies with the local assemblers?

yes you can swap the guages except for the gear indicator on the z200 and replaced w/ low battery indicator on the 250gs

thats right the second pic is an air pump or secondary air induction device, and it gets the fresh air it needs from the small air filter (1st pic) to mix with any unburned fuel from the exhaust and redirecting it again to the carb via inlet manifold for secondary burning for cleaner exhaust (emission compliance)...when that small air filter looks dirty just replace or clean with compressed air... just leave it open, if plugged or dirty will make your air/fuel mix rich and will affect performance....

i'm curious too what happened to your engine...i hope they replace it soon
no issues for me on oil consumption....

If you prefer diy work this might help….remove fairings and gas tank for more space, open the crankshaft bolt cover and flywheel timing mark cover with wide tip flat screwdriver, put some rug so not to damage the chrome covers, rotate crankshaft counterclockwise using 16mm socket wrench until the T mark aligns w/ a notch inside the peekhole  and piston is on top dead center (TDC) you can verify by removing the sparkplug…if a screwdriver sinks on the sparkplug hole, rotate another 180-360deg until piston is on topmost position and timing marks are aligned…use your feeler guage to check the gaps, the manual here says 0.07mm for intake and 0.10mm for exhaust…loosen the locknut, and feeler guage must have a bit of drag then tighten…replace cover o-rings if available (from auto supply stores)…hth

San Miguel beer

i'm here...and bit bored....

yes sir that voltmeter is only aftermarket add-on and i made also hazard light (switch on the upper part of panel)