Should you walk away? That depends on two things: the price, and your willingness to tinker with it and possibly walk away later.

The window is no problem, fixing that (or just changing out the mech for one from the yard) is easy enough. Probably just a dirty or broken switch.

The check engine light could be any of a number of things, ranging from a simple dirty connector somewhere to major expensive parts. Can you get access to it, maybe read the codes (check the 700/900 faq for how to do that and what they might indicate) ?

The lack of repair records is somewhat more worrying. How does the general condition of the vehicle look? Does it look like it was well cared for, or does it seem a bit of a run down dog? If it's otherwise OK, and checks out OK for the usual things (test run, idle running, cleanliness of oil, no water in the oil or oil in the coolant, no seeping/weeping block or gaskets, smooth shifting, everything working) and the price is right, sure, why not. If you have doubts, walk away. If there's major problems lurking it _can_ turn into an expensive nightmare. Of course I'm talking from a position of familiarity with the 900 series and being able to fix a heck of a lot myself, so even some maintenance catch-up is no problem (and a good bargaining point).

Bram