Thanks everyone. I bought it as second hand. new and cheap but it turns out there are two fungi. With my university student budget, I don't think it is worthy to clean it in pentax service center. Then after watching many examples of disassemble lenses for cleaning. I made up my mind to dismantle it. Yet its structure a bit different from primes. I　assemble it. It still works. I don't now how to deal with it. If not clean, the fungi will be obvious? Is it ok for put it together with other clean lens? I just quarantine it in a separate drawer. Then it turns out that there is two more spots. Shall I wrap it in a plastic bag and put it in a fridge? I will learn more and dismantle it and clean it later. Pity no such example in the youtube or google. Not such examples for disassemble DA zoom lens so far.Hong Kong is quite humid and hot actually.When I disassemble it, I find nowadays the lens are mainly plastics and not metal at all except for the rear mount ring.Morever the plastic are not as good as before. The hole for screwing tells that since it is crispy

Does anyone know how to disassemble DA55-300mm for cleaning fungus inside the lens? I tried to open the rear mount. Then find it hard to continue after take apart the amount. Besides, I tried to open the front glass by finding a notch in the front ring. yet none there. THen I take off the cover the front ring, and find some screws there. Unfortunately I failed to open the last two screws since they became damaged after unscrewing for a few times and they are stuck there? any idea?