Macro lens AF repairs

My now 7-year-old Canon 100mm f2.8 Macro USM lens has developed a problem with its AF motor.
The AF does not work, and when I half-press the shutter release and give the focus ring a full turn (in AF mode), I hear and physically feel the AF motor vibrating at a certain point during the turn - with no other sounds or vibrations before or after that point. In the past, AF issues have been resolved by cleaning the contacts. But this time it looks like a more serious problem, and the above observations prove that it is not a fault with the contacts.

The obvious solution would be to give it to Canon to have it opened up, checked, and have the faulty part repaired or replaced at a cost.
However, I almost always use my macro lens in MF mode. I have used AF on occasion (such as when shooting birds with this lens), but that is very infrequent. I think I would be okay with continuing to use the lens without the AF feature at all.

What I worry about, though, is the thought of something worse happening to the AF motor if this lens gets used (by me or anyone else) in AF mode while the motor continues to get stuck - can this cause more serious problems, such as something heating up or burning inside the lens?

To recap - Should I pay and get the AF motor in this lens repaired/replaced, even though I don't need its AF feature?

Is it impacting your aperture? For cleaning and inspecting the lens, they may charge a couple of thousand rupees. I think changing the motor would cost you about 7k or so.

Sabyasachi - No, as of now it doesn't seem to impact the aperture. The aperture motor had developed problems last year, and I had it replaced. (Let it not be considered the lens' fault - I use and handle this lens in rough conditions that only weather-sealed lenses should be subjected to. :))