A couple of weeks ago I checked the battery and at that point in time (after 160 load cycles) it still had a capacity of 5000 mAh.

Today, my 2006 macbook pro tells me via the battery menu to "Service Battery". According to Coconut Battery the current capacity is only 1590 mAh.

The corresponding help text suggests contacting an Apple Authorized Service Provider (AASP) to have the computer checked.

Before I decide to throw money at the AASP I'd like to understand what the AASP could possibly do to eliminate the problem. Isn't it more likely that the battery simply broke at 160 cycles and needs to be replaced?

Are there any means by software or firmware to influence battery behavior? Of course, the computer hardware might be broken but how could this result in the described effect?

And yes, I'm currently trying a calibration cycle but I have some doubts that it will save the day.