Can you grind or drill the head off the bolt so you can remove the adjuster assembly and deal with the bolt later? If there's no electric power available, use a cordless drill and center punch the head of the bolt, then use progressively larger drill bits to nibble away at the bolt head. Once most of the head is gone, chisel the rest off.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!