Better buying new.
There are some good ones out there.
Finding the ones with better motors are hard as they fail all too often.
Search gutter vacuum system and you may well find a firm very close to yourself who sell the old omnipole vacs.
Just worth saying though they are not easy to get replacement motors for. Saying that they should last a few years.
Easier to just replace with a new vacuum head and use all the poles and the drum.