Acer Aspire 1690 power problems

Hi, I bought a laptop off adverts.ie 10 days ago and I’m having trouble with it.

The guy told me when I went to collect it that the original charger broke and the replacement (a lite-on) one he was giving me wasn't a great fit and would have to be pushed in a bit more, or something along those lines.

Anyway, the jack on the charger has to pointing at a certain angle to work and is very temperamental. This morning it stopped working all together (no matter how much I moved the cable and turned the jack) only to start working when I plugged it in again a few hours later.

I was going to order a new charger but then I remembered the DC on laptops can be problematic.

Is there a way to tell if it’s the charger or the laptop, if it’s the laptop I’m going to try and return it. If it’s the charger I can get a new one.

I posted in the laptop forum last week and never got a reply.