I have a 9 year old MTD lawn tractor w/14.5 Briggs & Stratton. It
starting having issues turning over at the end of last season and I
attributed it to a battery going south. Once it'd start it ran great
however. Now this year it'd turn over *real* slow once, maybe twice
and that's it. Replaced the battery since it's a few years old, but
same result.

I pulled the spark plug and it turns over easily. Put the plug back
in...problem returns. Could this is be an indicator of a valve
problem (since problem occurs with compression) or just a 'weak'
starter?

Any help is appreciated.