So you can (should be able) order a cleaning kit from Takahashi of America or Similar in Australia or Japan.
Dedicated application cloths.
And if you need it a blower bulb (Rocket or other). And you'll need distilled water
Takahashi will send instructions.
Most important is nothing gets wiped. The lens gets dabbed with enzyme cleaner. Form tent/bulb with cloth, wet it with cleaner, dab.
Then you follow up by doing the same with distilled water, dabbing no wiping.
Need to be sure the cloths aren't saturated as to where liquid can drip toward or into the edges and be pulled into the cavity between lens and tube.
I've used the Takahashi America Cloths and Enzyme cleaner along with distilled water and used the blower before and after cleaning. And the lens will clean up very nicely.
Remember don't get aggravated by specs of dust to even a finger print on the optical tube objective lens. Do Not use a wiping motion or any motion that drags across the lens.