DCPowered

if its riveted you'll have to take the whole cover off , it should be at least four bolts 2 on top and 2 near the bottom of the cover.  There are metal tabs that pop out when the recoil string is pulled most likely they're stuck or broken, if they're stuck try some spray lube, like Fluid Film in where the metal tabs pop out, first try without taking the cover off,  after that jerk the recoil string a few times if that dosen't shake them loose then try taking the cover off to get a better look.

I found out with these new china built engines they don't sell individual parts a least not the people our shop buys from, an example being if anything breaks on the carb they send a WHOLE carburetor,  a guy brought one in, the recoil spring needed replacing (brand new MTD Bolens single 21inch) they don't sell springs they just send a whole new recoil, and for cheap.

If your looking for longevity in your snowblower I'd suggest staying away from blowers that use too many plastic parts  MTD does this a lot, also I personally prefer to have steel rods and no cables connecting the drive and auger handles to the snowblower,  cables tend to break on blowers that are used frequently.   As another personal preference I prefer a tecumseh engine over Briggs and Stratton because if your a do it yourselfer they are a lot easier to work on and get parts for.

It could be one of a few things

A) if you flip the blower on it's nose, and take off the bottom pan, check to see if the rubber drive disc is slipping when it hits the friction disc, you can do this by engaging the drive handle and if its working properly u shouldn't be able to move the tires, if it is slipping, clean off the friction and drive discs of any oil,grease or water.

B) Rubber drive disc under blower is wore out or has chunks missing, you'll have to replace it.

C) the drive belt is wore out/stretched, check by taking off the belt cover right in front of the engine, drive belt is the one closest to the engine, check for wear/ cracks or rips  (yours may not but some blowers have a tension pulley to keep the drive belt tight if it does check to see if it's doing just that)

D) The rod or cable which ever connects the drive engaging handle to the drive could be loose and require tightening, its usually a threaded piece at the bottom of the rod or cable



As for the gas leak, it's common for that to happen, it just means you've over primed and the fuel bowl is full so the gas has no where to go but out of the larger open port on the carburetor