If the top half of the jar is relatively free of the contaminant, it would be very possible to use the "clean" spawn to innoculate another substrate...use leached cow or horse manure and pasteurize it. Manure is much less susceptible to wet spot than grains are.  You need *dried cow or horse patties*...nothing you can buy in a store will work.   Pasteurize at 180f. for an hour, strain, cool, add gypsum, innoculate, throw in a tupperware on top of some vermiculite or perlite (to absorb excess water), pat down, cover with moist, clean, white towell, and put the lid on until spawn runs thru.  When surface is completely white, scatter vermiculite on top and remove lid and expose to light..leave the towell on and keep it moist.  This method will greatly increase your yield relative to jars.  In fact, i highly recommend doing this with all your jars, regardless of contamination.....no promises with the contamination, but you might be able to salvage it if you're lucky....good luck!