Before you dispose of the saw, get a good hollow ground blade for it, and try one more time. Also, these saws are not intended to be a primary saw. They are designed to make scroll cuts, not long straight ones. With a good blade, this saw might surprise you.
The problem you can get into with brand names is the so much of the World is sub contracting to China. China has Zero Quality control, and they make mostly garbage, as a result. I recently bought a DVD player from Sony to avoid China manufacture. When I unpacked it, I noticed two things, it only had a 90 day warranty, and it was made in China! It lasted about 6 months....
It is not my primary saw. The problem is that the blade falls out of the guide roller so it will not make cut a perpendicular to the surface. Thanks for your comment.
I just had the exact same problem, and found out that the blade was the wrong blade for the saw. It seemed to fit, but when it hit wood, the blade pulled out. Your saw looks just like mine. I found it is made for a T Type blade. When I got the right blade, it worked well. I still have the bad blades, here is a picture.
The one on the top is the T type blade, the bottom is the one that locks in, but won't stay.
I will try it.
Best of luck!