I'm looking at some used CST 280 DC stick/tig welders. Was wondering if there is any difference in the ones made back in 2005-2008 versus the new ones made in 2013?

Looks like these older welders with a few leads can be had for in the range of $800 to $1,000. Not sure if this is a good buy or if these welders could be at the end of their life span since they use IGBTs?

Are these circuit boards potted to prevent problems with moisture or dirt exposure?

Has there been any changes to the circuit boards that would make repairing a older unit difficult if it ever needed it? Like compatibility issues if older than a certain serial number.

Unit I'm currently looking at is S/N:
LH400095G

Can history on this unit be pulled up and checked for history of services or repairs if they ever occurred?

How expensive could it be repairing a CST 280 if things like IGBTs go bad? What is the worst that could go wrong?

Looking at a unit with Tweco connectors, but not sure if I should wait for a Dinse style unit since I want to do some tig with the unit too.

Thanks you for your help!
Clint