A well tool having a magnetically coupled position sensor. A removable lid is secured over an opening to the container to enclose the liner. 3, the core region of the fiber can support a plurality of modes at the pump wavelength, and the cladding region can comprise at least two air holes extending along the length of fiber wherein the ratio of the diameter of the air holes to their pitch is greater than 0. At the bifurcation, the side branch guide wire is freed from the flap to advance into the side branch vessel through the stent side port. The cartridge preferably includes a housing, a roll of film, one or more rollers, a creasing finger for creasing the film, and two or more opposed extensions for folding the film along the crease.