Hello gadindixie,
When you post a help request, we need the stamped number information in the valve cover of your "17.5 briggs". They are not all the same.
Is it cranking, but hitting a dead stop point, or fighting the starter? The most common thing is that it needs the valves properly adjusted. double check your adjustment.
A quick check of the compression release is to remove the spark plug, then the valve cover. rotate the engine by hand on the flywheel screen while watching the valve movement. The valve should open and close about the same. The intake valve should have a slight activation "dip" just before the valve fully opens. If you see the dip, the compression release should be working. If there is no dip, the compression release is hanging up or bad.
Teryl Fixes all has a lot of You Tube videos showing how to check the cam operation and adjust the valves.
An oil change would be a good idea if you have not done one yet. (If the compression release is working.)