Using a blow torch and the steering wheel.
And to see the whole process in moving pictures (they don’t always start this easily...)
Why the steering wheel? Well, turning an exposed flywheel is a potentially dangerous activity so you cover it up. You still need to turn it and you don’t want to fit a starter, dynamo and battery so you leave a little flap for access. You then need some kind of turning thing to use to turn it. The steering wheel is to hand and turns.
Lanz, makers of the Buldog, were bought by John Deere and gradually became John Deere Deutschland. The bigger Deere models are still made in the Lanz plant in Mannheim.