I put the shaft into the housing, placed the spring on top with the cap, used a "C" clamp to press it on and it worked..... Sometimes when things don't go together on the old Triumph, I use a hammer and realize the Brits instead of spending money on tapping out the hole for a nut and bolt, they just press things together.
Just make sure that the aforementioned hammer is big enough to cope with the vagaries and idiosyncrasies of old Brit bikes. Nothing smaller than a 5 pound lump hammer (aka a Yorkshireman's tweezer) will suffice.
