On the 834, the stitch LENGTH knob is set near or at 0. It won't feed there but things will move. I can see the little red dash on the opposite side of the knob. The red dash is near the longest stitch end.
On the 410, put the face plate back on it so you can run the thread through the guides.
It looks like it uses the Apollo (plastic) bobbin case, if so you should be using plastic Class 66 bobbins. But it won't hurt if you use the metal ones.
When the full bobbin is in the case with the thread through the tension spring it should rotate counter clock wise as you pull on the thread.
To set the thread tension remove the bobbin case, put a bobbin in it and thread it through the tension spring. Hold the end of the thread letting the case dangle. Does it fall away? No, then gently loosen the tension screw until it does. Then tighten it just till it doesn't. Hold it out and jerk the thread just a little bit. Does the bobbin case drop and stop? If yes put it back in the machine and thread it up. If no tighten the adjusting screw just a tiny bit and repeat until it does.
If you've done all these things and the bobbin tension is still too tight, the bobbin case might need to be cleaned. Put it in a zip-lock bag and carefully remove the tension spring. ( That way you don't loose those tinsy itty bitty screws ) Clean it and the case well. Reassemble it. Run the attaching screw down tight, but not too tight. Turn the adjusting spring down till it stops then back it out 1/2 turn. Do the same thing as I posted just above to test and set it.
If none of this does anything then there is something, dirt, lint, thread, a busted needle ( I found one like that) interfering with the thread travel.
Joe