Ah, a Dura-ace 10 speed chain cost me $45...... Wanted to buy a chain tool so I could do such operations in future myself, but didn't like the $30 price and overkill-looking tool.

Anyway, it was a little sad, cos my chain had already stretched and affected the cassette, so changing the chain actually caused a slight drop in shifting performance instead. But better than continuing to eat the cassette out...

Moral of the story is:
1. Frequently degrease, clean, and relube the chain
2. Keep track of chain mileage and use a chain stretch tool to check frequently after 2000km (every 40 group rides?)
OR
3. Just change the chain every half a year of regular usage. (ie annual expense of $90 just for the chain)