Small Engines (Lawn Mowers, etc.): Riding Lawn Mower will not start, briggs and stratton, hp briggs

Question
Sorry. I forgot to mention that I had also replaced the battery. In fact, I was originally on the same track as your answer. I had replaced the battery about 2 months before the problem began, and took it back to the store for a warranty replacement with another new battery once I began having the starting problem. Unfortunately, this did not solve the problem. I also tested the alternator, and it is charging within the engine specs.  Any other suggestions would be appreciated.------------------------
Followup To
Question -
I have a 4 year old Ranch King riding mower(built by MTD) with a 16.5 hp Briggs and Stratton OHV engine. I have always been prompt with preventative maintenace. Late last season, it suddenly would not start. The starter turns the engine about 1 revolution, than acts as if the engine is stuck or has too much compression. By hand, I can turn the flywheel past this "sticky point", and it will turn easily for about another turn. With the spark plug out, the starter spins the engine with no trouble. This occurs even when I remove all drive belts from the engine. Thus far I have replaced the following: all filters, starter, ignition module/coil, solenoid, ignition switch, spark plug, muffler, and the carb. I also completely drained the fuel tank and replaced it with fresh fuel. I also pulled the flywheel, and found that the flywheel key is o.k. I have also drained the oil and carefully measured the amount I put back in, ruling out oil/hydralic lock. Likewise the new carb. made no differance and there is no excess fuel coming out of the the spark plug hole, so I have also ruled out fuel/hydralic lock. With the use of a compression guage, the engine builds up a compression of about 65 psi. I have also tested all the safety switches on the mower itself,and they are all working correctly. By pure accident, I found that the mower will sometimes start immediately if I do the following: I set the throttle and choke controls to the normal starting positions,  but while turning the starter I manually hold the throttle plate on the carb. in a closed position, letting it spring back open when the engine catches. This works about 80% of the time, although sometimes I also have to turn the flywheel by hand past the "sticky point" before even this procedure works. Once I get it running, it appears to run fine. As you can see, I have nearly replaced everything on the outside of the engine. Am I looking at a rebuild, or is there something else that I am missing? Please help, this mower has become my arch-enemy over the past several months. Thank you
Answer -
Hi Doug,

The holiday has delayed my reply, sorry.  
You didn't mention the battery.  Try jumping it with a vehicle or a known, good battery and see if it cranks over well.  Fast and proper cranking may allow for good starting.

Let me know.
Michael

Answer
Hi Doug,

Very strange.  I don't see what is preventing the engine from cranking.  Maybe the starter is weak and defective or there is a bad connection.  The compression is low, so that shouldn't be a problem for a good battery and good starter.

Michael