Small Engines (Lawn Mowers, etc.): Lowe Rear Tine Tiller wont start

Question
I've got an old rear tiller with Lowe stamped on the belt cover plate. 5.0 HP engine (chain drive power reverse) model 130292 type 3111 01 code 90102527. Will not turn over: new plug, new air filter, recent oil change. The cables are new & the carb. has been rebuilt. I tilled my garden 3 times successfully, but on my 4th till it stopped after about 3 rows & would not start. 2 hours later I tried again, it started, but stopped again after 3 rows. Now...nothing. I've used carb cleaner, starter fluid, etc. Replaced plugs several time. Nothing.

PS The engine was rebuilt before I got it. Has a history of being hard to start & fouling the spark plug.

Any ideas right off hand?

Answer
Do you know what was done to the carburetor?  Some of those carbs can warp over time and cause hard starting.

Will the engine start if you use a squirt bottle with gas to prime the engine?

How much compression does the engine have?  Tiller engines run in a very, very dusty environment and will wear out the rings and valve guides leading to a loss of compression which can make the engine hard to start.  

Eric