Hi chaps,
I've never owned a 70, a situation which I will have to address one day.
Neither have I ever worked on one.
Now, and I might be MILES off the mark here, so do apologise in advance, but the OP states that it's a Mark 1....... I'm just wondering if these earlier examples used a leather piston seal and if that's the reason why the replacement seal is nothing like the original?
As above, please excuse my ignorance if incorrect....just a wild guess???