My beloved 1985 SJ413W (LWB softop) is frequently left parked in the shed for two or three weeks at a time, and when I know it's going to sit for a while, I disconnect the battery.
When I recently reconnected the battery and hit the starter it gave one spin and died, then everything was dead. Disconnected battery, reconnected, same thing, this happened several times. Took the battery to be checked, it read 14 volts so should have had ample cranking power, the battery shop was saying "Oh, you must need a new one!"
Not happy to do that, I brought it home and kept on tinkering, but still no joy. Then I suddenly remembered something I was told years ago (can't remember by who).
Got my can of WD40 with the little pipe thingie attached and squirted a generous amount into the ignition lock - turned the key again and it started!
Has started perfectly every time since then, I do recall the original tip being about cleaning crap away from the contacts in the ignition barrel.
I keep forgetting to drop into the battery shop and tell them how I saved the cost of a new battery.
Cheers - Longbaser.