What exactly is a Yale No 3 padlock? Any pics of it?
When picking padlocks, remember to use a bit more tension than you would normally use for a regular cylinder. This is to overcome the internal spring mechanisim of the padlock which pushes out the bar/ball bearings.
A typical Yale I picked yesterday has double locking ball bearings (so no shimming possible) and a standard 5 pin plug. Applied firmish tension and gently went along each pin pushing down slightly. Pins 4 and 5 clicked. Then i repeated on the first three again until they all clicked. When pin 3 clicked there was a definate turn of the plug. Checked all the pins again and 1, 2 and 5 seemed solid. Pressed 4 down gently while easing tension off slightly, plug slightly turned anti-clockwise, and it clicked. Repeated on 3 and more noticable backwards plug turn evident and suddenly it popped!
and here is me applying firm tension......
The hook i used was a small pofile HPC one (dunno which model) while the tension wrench is a slightly ground down wiper insert, ideal for small padlocks.
Persevere with your tensions and learn to spot the tricky pins! Good luck
regards