Small Engines (Lawn Mowers, etc.): solenoid not juicing starter enough..., cable ends, key switch

Question
Scenario: 11.9v at battery. 11.9 volts to solenoid. Tested secondary wire from solenoid(post on batt. side) thru fuse to key switch...11.9v. Tryed to start mower(MTD 14hp/42") and getting only quick burst of voltage at starter motor; barely enough to raise gear to flywheel sometimes. Ranges between 4-7 volts by my multimeter, and lasts only a split second; even when keeping the key turned to start position. 3-prong solenoid, so grounding isn't a problem there.

Thanks in advance and God bless,
Wes, USN-14yrs.

Answer
Have you load tested the battery?  Have you dis-connected the battery cable ends and cleaned both the battery terminals and cable ends with a wirebrush?

Did you check and clean the negative (ground) connection?
How old is the mower?
Did you problem happen suddenly or has the mower sat a while?

Let me know.
Eric