Buying a used Kickr

I’m looking at buying a used Kickr to save some money. I’ve found a few on various websites - some local, some not. What’s the general thought on buying these used? Is it risky? What sorts of things should I look for as red flags?

Wahoo sells refurbished Kickrs.

Wahoo sells refurbished Kickrs.

Yep - $650 with free shipping. (I bought one last year)

Link

oops - out of stock right now.