"PCR machines ABI 9600 breakdown"

[z]

Hello, 

here in the lab we have 3 perkin elmer (or abi now-a-days) 9600
PCR machines. These machines are very expensive (appr. DM 20.000)
but up to now i was very pleased with the way they are functioning.
but last week, one of these machines broke down and apparently the 
cooling system was damaged. abi told us that we have to send it in: 
you can guess what that will cost. 
just for fun i tested the other two machines also: one of these also 
failed the chiller test. These machines cool noticably slower.
machines are between 2-4 years old.
Question: does this happen often, even with machines that are not too 
old in my opinion ? what can we do to stop this from happening ?
any other kind of advice welcome.

Clemens Suter-Crazzolara, PhD