setting the pinion correctly is difficult for an amateur to do. its a skilled job to get it just right. some experienced mechanics cannot/wont do it.
its not impossible but it does take some time.
you will need a workshop manual at least.
the older ones dont need any electric. esp with a mechanical fuel pump
newer ones have either an electric fuel pump and or an electric solonoid on the IP. in which case if you pull the main earth lead off itll stop.
quickest way is to put it against a wall and let the clutch out in 4th/top.
24v electrics prob the only real major difference.
not all of course there were some 12v ones too. lighting circuits are diff.
and a lot of civilianised ones have been converted to 12v anyways.
the rest is fairly minor stuff.
id say it was ****ed.
u can try and squirt some wd40 in it wif that little red straw thingy.
if that dont work then a new lock barrel assembly looks favourite.
if you mean concept asset management on stoneclough rd, then yes ive seen them. only bout 4 miles from me.
but sorry i know nowt about them, good nor bad.
also seen some adverts for their used cars/vans, and they do seem expensive?