Electric Furnace, no AC, blower motor starts then slows after 1 second
I would be looking for a run/start capacitor it sounds like the start side is good but when it changes to run that one may be bad. Another thing is to lube the bearings there may be small ports in the front and back of the motor that you can drip some motor oil into, blowers don't require full torque until up to about 75% because they are not pushing much of a load until that point but a capacitor would be my first check unless you see the ports and have a oil can handy it only takes a few drops.