deadline;361362]You have an electrical issue. The motor *could* be out of time, or the distributor 180deg out, but I am starting ont he premise that the motor was running, you just experienced slow starting.
My jeep starts wonderfully on 6v and an original WWII starter.
Go to the store get a tube of dielectric grease. A small tube will suffice, also you will need a commutator stone. DO NOT USE SAND PAPER. Also a small wire brush (toothbrush sized is best).
Starting at the copper lug on the starter, take off the nut and wire, clean the copper lug and end of wire with brush. Make it shine! Before assembly dab on the dielectric to the copper lug and make sure you use a NEW star washers. Work your way back doing the exact same thing at the foot switch then battery terminal. Then go from the ground pole on the battery, to the ground strap, to the grand strap to frame bolt.
Try starting again.
If it doesn't start, or is very slow take off the starter, remove the brush cover and take out 1 brush from the holder, use the commutator stone to make the commutator shine. Inspect the brush (should be at about 2cm long and flat at the tip that rides on the commutator and commutator proper. If either has deep gouges or worn irregularly they need to be fixed/ or replaced.
That's all there is to it. Your 6 volts needs a very low resistance and corrosion/dirt/grease on the contact points is the number one reason for slow starting.
Now if your motor didn't start freely BEFORE the new starter then its something else.
You might need a new foot switch, but try this first... 90% of the time cleaning the grounds and polishing the commutator solves the issue.
Thanks for advice will try cleaning contacts up