Ok. The hub fitted is the right one. Though you'll need to post a pic showing whats short about it :?, as im not sure what you mean.
As to the spring, sorry havent a clue, but it should be noted that as the arm is operated, the spring should tighten. Might just be a case of its shape, and maybe winding it tighter and refitting could do something. I take it by 'coming off' you mean the loop ?. As its secured to the arm, and the other side is behind the cable.
Could it be theres too much slack in the system ?.
Possible to take off the actuating arm and place something like a wide washer behind it. That way at least the spring would be held in place, but ive no ideas there really as to why it should want to come off. Again speculation, maybe its bend. So perhaps sit, look at it, work the arm and see how the loops of the spring move, and maybe bend them or twist the end bits.
As to the spring, sorry havent a clue, but it should be noted that as the arm is operated, the spring should tighten. Might just be a case of its shape, and maybe winding it tighter and refitting could do something. I take it by 'coming off' you mean the loop ?. As its secured to the arm, and the other side is behind the cable.
Could it be theres too much slack in the system ?.
Possible to take off the actuating arm and place something like a wide washer behind it. That way at least the spring would be held in place, but ive no ideas there really as to why it should want to come off. Again speculation, maybe its bend. So perhaps sit, look at it, work the arm and see how the loops of the spring move, and maybe bend them or twist the end bits.
