aperture adjustment on nikkor sw 90/8

while the aperture adjustment on each of my other lenses has a certain amount of tension/stiffness (ie, it takes some effort to move the lever, and it tends to stay where you put it), the adjustment on my nikkor sw 90/8 is quite loose - the lever offers little or no resistance, so it is easily knocked out of adjustment if you happen to brush your finger against it when you cock the shutter. the p roblem is exacerbated since the lens is mounted on a recessed board and it is al ready tricky enough to access the controls (at f22, the lever is inconveniently located directly behind the cocking arm, and is quite a pain on occasion). is t here anything i can do to address this problem? thanks.