For safety reasons, with a 4-year old helmet in Thailand, you should better be looking for a new helmet. Lots of people in Thailand don't take the daily UV-rays on plastic serious, but trust me, UV-rays have a very destructional effect on plastics – and in Thailand we get a lot of UV-rays.
While I did years with plastic garden furniture in my home country, it seems that I will be lucky if I get one whole year out of the stuff I have now out in the garden... It becomes so bros that putting down a beer bottle will scatter the whole table in thousands of pieces...
If a manufacturer says 5-years, I start start casually looking for a new helmet after its 3rd year in my possession...
If In BKK. Go to or call Paddock, see if they have any cheek pads. Very near MRT. While you are there you may find you fancy a different helmet!
Somebody knows the washing instructions of helmet pads?
3 Comfort Padding
Removable parts should be removed and washed by hand or in a washing net in the washing machine. Fixed padding should be wiped with a damp cloth, again using only a neutral cleaning agent. After cleaning or washing, all parts should be thoroughly dried out of direct sunlight in order to prevent the development of unpleasant odors.
By washing net they mean the mesh bags from Tops, Tesco etc for delicate items.
I have a Shoei helmet, guessing about 4-years old, and I found the article 'Shoei Helmet X-Spirit replacement cheek pads' and was wondering where you bought them?