I used to have that problem on my 70 westy for some time.
The fix was to use a relay kit that I bought for about $10. from Wolfgang
intl. or busboys.
It was easy to install and the problem is now solved.
My first fix was to crawl underneath and jump the solenoid with a stubby
screwdriver.
the next fix was to run a pair of wires up to a switch on the dash to use
when the ignition-switch did not work.
So add yourself a relay, then the problem will go away.

63 singlecab
(Dove Blue_ Kleine Blau)
70 westy

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