as i said rl sensor is shot, while still waiting for t new one, i decided 2 check out t old one, they truly are sealed so its possibly not worth a fix, mine was dry inside and perfectly clean so i dismantled further and found that t running strip where t 6 little fingers run had worn into it,so no repair here, all that i now could do was too try and make a front one that i had 2 to fit t rear, its now fitted and working except on extended height . but as of now its a quick fix to get me out of trouble.