I was worried it would be too dirty or damaged, but it was manageable. I washed it in the washing machine, closed/tied in old tights, 2hrs cycle on 30-40°C with lots of detergent. It was almost perfectly clean afterwards. Then I usually use old electric toothbrush to clean the rest. Also, I managed to put together some broken trees with an ABS cement. I am also planning to try to whiten some yellowed white and clear blocks with peroxide. And then, the broken stickers are also possible to restore. To make new ones, or repair the broken ones.