According to the owner's manual, the correct oil/gas ratio for a Toro s200 snowblower is 32:1, or 4 ounces of oil for every gallon of gas.
32:1
.030
compression of a toro s200
50:1
Plug is Champion RJ18Y. Gap is 0.035 This is on page 12, in maintenance section of Toro S200 Snowthrower operators manual. Checked at local Advance Auto Parts store here in upstate NY (south of Rochester) and they cross referenced this plug and said to use Autolite # 86, Price $1.69 + tx
The correct ratio for that particular snowblower engine is 50 parts fuel to 1 part two-stroke engine oil.
There are many places one can purchase "Toro Snowblower Parts." In addition to the official Toro website, one might also search the auction website, eBay.
WalMart
You can find parts for a toro snowblower at WalMart. WalMart is a store that sells many items online. You can purchase a snowblower and parts from WalMart and they will have it delivered to the store for free or to your home for a nominal cost.
32:1
it is going to depend on where it is leaking from
The spark plug may be fouled. Remove the plug and check to see if it needs to be replaced.