Mandrel for 306/-2 (1/8 in) and 471-2 fitting?

I am doing my instrument lines and haven't found a small mandrel for the size
noted above. If the mandrel is not available for this small hosing how do you
put it together? I don't want my hose to fail. I am replacing the old ones as I
found some very lose hosing including to the fuel pressure gauge at the fire
wall which I think was only a matter of time to fail. It looked like the
fitting was not put on correctly as the 2 pieces of the fitting were "frozen"
and the hose was pretty loose to the point of just pulling it off with no
effort.. Thanks

Larry