Cost of removing mould

Hi there, on my 100-400mm lens, some mould has begun to grow.

It is on the inside of the outer most element of glass (underneath the lens cap)

It is only very small right now, about the size of an ant. Obviously it will need to be taken apart.

So how much will this cost me, and are there any places you would recommend. Or better yet, is there any DIY way of doing this without much risk?

thanks

Once mold (mould) has begun to grow in the lens, it is inadvisable to selectively remove it. Ideally, the entire lens should be disassembled and cleaned. This should only be done by a Canon service center.

For future reference, the key is to prevent mold in the first place. Absolutely invest in reusable color indicator silica gel packs, use them often and place them in all your gear bags. If you live in a humid climate, even this may not be enough--a dedicated sealed drying cabinet is a must for lens storage. Once mold has gained a foothold, the glass surface has already been etched, making repeat growth more likely, and the element is permanently damaged.

Because of the push-pull design of the 100-400, it is more susceptible to dust, moisture, and mold problems than lenses that are internal zoom/focus.