Just another thought.
How about some kind of another foot stomp pedal, to be placed under the down stroke pedal.
It could be used to to help raise the blade back up.

Just trying to think outside the box and make something work.
Don

Edit: If you opt for trying out the garage door spring. Check out your local garage door repair shops.
They probably just take used ones to the scrap yard.
Hook one end to the pedal and the other to to the rafters.
Just a thought.
Don

Last edited by 2-Ton; 05/18/2018 3:25 AM.
1967 GMC 9500 Fire Ladder Truck
"The Flag Pole"
In the Stovebolt Gallery
1946 2-Ton grain truck
1946 3/4-ton pickup,
1953 1-ton pickup
1957 1-ton flatbed dually,
1954 Pontiac Straight Eight
Of all the things I've lost in my life, I miss my mind the most!