Starting problems

Hi, I wonder if anyone has any thoughts on our starting problem. We get an intermitent fail to start where the engine does not turnover and you can just here the solenoid click. We have had the starter motor off and lubricated it and freed it up and re-fitted and started the engine. It will start numerous times but if then run the engine under load and come back to mooring and stop it will not restart. Can then take the starter off and work it and re-fit and it will start. Anyone any thoughts on why this may be? Thanks for any ideas

may help by stating who's make/model/type you are dealing with...???

Could be a bad connection that won't pass enough current or the brush holders just need a thorough cleaning...or a few other items...

The solenoid disk and contact points have bad spots. The contact points go to the battery cable or the starter. When you energize the solenoid a copper disk that spans the two contacts, moves to touch the contacts and initiate electrical flow. It's high amps, and the disk and contact points get pitted. The disk turns slightly each use so it lasts longer. Once the points or disk is pitted, sometimes the solenoid won't make contact. Sometimes the high amp flow will cause the points weld to the disk.
The fix is a new solenoid or take the solenoid apart, file the points and disk down to unpitted metal.