We quickly lost count of how many tech calls we have recieved from customers with broken rocker arm screws stuck in the rocker shaft. It's a common cause of frustration when rebuilding a Samurai 1.3L engine. The phillips head screws used by the factory are simply not strong enough to remove without snapping apart. Often a screw extractor can retrieve the broken portion of the screw so that the shaft can be removed from the head though sometimes the entire shaft needs to be replaced.
When you rebuild your Samurai's head do yourself a favor and toss those problematic OE rocker screws. Low Range offer a set of Heavy Duty Rocker Rod Screws that will not snap under removel tension. These screws also use 4mm hex socket heads instead of phillips heads. This assures you will not destroy your rod screws if you need to rebuild your head.