In the limit of weak collisions, a narrow boundary layer forms at the trapped/untrapped boundary in velocity space. When the electron collision frequency &ngr;eis small compared with the wave frequency &ohgr; times the inverse aspect ratio &egr;, a realistic collision operator must be employed to evaluate the response of the boundary layer electrons. The parallel current carried by the barely circulating boundary layer electrons results in tearing mode modifications which are evaluated from a slab model in the banana regime (&ngr;e<&egr;&ohgr;) by using a Lorentz model collision operator.