Small Engines (Lawn Mowers, etc.): B&S 18.5 hp hard turning over, autozone, riding mower

Question
Model 42A777 engine on riding mower turns engine extremely slow.  With plug removed, slightly, but only slightly better turn-over.  Can turn over engine easily by hand.  Pulled apart starter, (bs-498148) but looks to be nothing wrong internally.  Could it just be a bad starter with the coils/windings going bad?  No cracks in the magnets,and cleaned with wire brush/emery all contacts.  Same results.   Seeing all over internet that new starter solves this problem.  just don't want to waste money in the meantime.   Appreciate any and all help.   BTW- Battery is good, reading 12.6 volts.  Not sure how to check the amperage, or whether I can check the voltage at the starter while key trying to turn on.  Should I have the same 12 volts AT the starter?  If I don't, what should I look for.

Answer
Well Clay, first things first. 12.6v at the battery actually means nothing at all. It's amps that push the voltage. You can have 12.6v and 50 amps, and then have 12.6v and have 800 amps. I run into this a lot when people at my shop buy their own batteries. The look for the least expensive they can find. They are not comparing apples with apples. You must look at the cranking amps, and determine if they are the recommended amount of amps by the manufacturer. Your battery very well could be junk. It may show the right amount of volts but lost it's ability to provide the right amount of amps needed. Without the right meter you wouldn't know if this is the case or not. I would try fully charging it then bringing it by Like a Autozone store to have it load tested they usually do it free. It could also be the winding in the starter of course, but you always start your troubleshooting in the right steps, that's the power supply first. Let me know if you should need more help on this issue....Tom