Hello there, it is me from the suggested link...
I did all that was said - cleaned all connections... it is true, the starter was underneath just where all the crap and wet is constantly thrown up. I wish I could say "I fixed the exact problem" but I can not.
Although I have not had any problems with starting it for the last few weeks after cleaning various connections, I cannot say which one was too blame.
All I can say is that the "pull" of the current is very high to turn the beast, if it can meet resistance or go elsewhere - it will. You have to make sure the path is true and clean (famous si-fi words it know) but sometimes a "good looking" (no I don't find them attractive) connection is not the best, high amps will throw a connection apart rather than jumping and you can get a clicking from that.
I am no expert but - advice is to clean and check all connections... and be careful about hitting anything - it may work - or it may crack and break something then you will need new parts.
It took a few times to gain confident to turn off my van - worrying about it starting again, but funny how you forget the stress a few weeks down the line.
I hope this helps in some small way.