Spinning Wheel - Bearings - Wheel is very hard to treadle

Usually this occurs because the bearings have been oiled and are now gummed up or ceased.

A good cleaning is needed.  Take a look at this article regarding care and maintenance

 

Steps to check your wheel
Take the drive band off and just spin the wheel. Does it want to keep turning or does it want to stop turning? If the latter, that confirms the bearings are preventing movement.

1. First, remove the footman exposing one of the bearings.
2. Remove the bearing - either a screw connection or a bolt connection. Keep track of the sequence of parts.
3. Take the bearing and wipe it clean with a damp cloth.
4. Hold the center core of the bearing with your thumb and forefinger and turn it. Doesn't it turn smoothly? Are there any rough spots that you can feel as you turn it? If so, you need to replace the bearing.
5. Next, remove the main wheel. Keep track of the sequence of parts.
6. Once removed, you have exposed the two bearings in the back post.
7. Use a screw driver and pry the bearings out of the bearing cups.
8. Clean these bearings as well. Replace them if they are flawed.
   
   
   Once cleaned, replace the bearings in the back post and replace the main wheel.