If you can get the parts, take a look at this.
http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/182022-hot-start-relay-kit.html
Hot start has been a problem for years.....whacking will gwt you going, this will cure the problem short of replacing the starter.
I've used a Ford relay in some cases. Oh yeah...get a jack, too.