Bought a Bobcat Leo w/ 17.5 B&S about a year ago. It's the ELS 500 motor model#31L777-0110E1. It's VERY hard to turn over past the compression stroke, and has burned up 3 starters because of this. Less than 200 hrs on it, and been to the dealer many times. Called B&S and had the cam and compression relief valve replaced, but didn't fix the problem. (Evidentally, there was a service bulletin out for this) They "fixed" it for free....but it didn't help. I'm thinking of just buying a new motor out of pocket.... IF I do, what should I be looking for? Does the wiring harness of the new motor plug right up? I doubt it! Here's the specifics: 3-5/32", 1/4" keyway, 7/16-20, 1" diameter shaft, keyway, alternator is 9amp I think....does it matter what amp it is? I do not know what all of these mean, and all I could find were the specs for the 31L777-0036 motor which I guess is the newer replacement of my current motor. I guess it became obsolete? The mower is about 3-4 years old. I assume I have to replace it with a B&S because of the bolt pattern on the mower? I have been looking at the Vanguard 18hp. I really would appreciate any help. I plan on spending around $1000-$1500 total. I can install it myself-I have basic knowledge and it seems pretty easy. Thanks a lot!!!!