When you say, "Hear it trying" can you be a bit more specific?
1 - Single
big "CLICK" and nothing else?
2 - Little click, click, clicks repeating in rapid succession?
3 - Click and sound of engine
rotating but no start?
And by "the hammer trick" do you mean "tapping" on the starter or solenoid?
In general troubleshooting.
- Batteries charged
- All electrical
connections tight and clean at batteries, switches and starter - remove polish and reinstall for good measure.
cable to starter in good shape - see photo
for "bad" shape. Cable will be "ductile" and firm but not "sloppy" like overcooked pasta.
- Ground cable to engine in good shape - as above
- Starter solenoid suspect - "no click"
- Starter bendix "stuck" - Click, maybe sound of "whirring" but no gear
engagement to flywheel
- Starter suspect - Click, no rotate. Dirty/corroded armature, failed contaminated armature wiring
Photos - My ground cable from last year. This cable laid in the bottom of the bilge
and until we pulled it out "looked" OK - The engine was still cranking and starting even with this much damage.