The maximum course size that Chase! will successfully run is about 100 feet. That's 25 feet per side for a square course. But your actual course size may be a bit smaller based on the specific conditions for your setup.
If your drive is running erratically, jerking, or hesitating, or won't run at all - the drive is being over worked - so the first to do is determine your maximum course size.
To determine your specific maximum course - start with a small course of 60 or 80 feet (ie: a square 15 or 20 feet per side) or smaller.
Once you get a smaller course running as expected, you can gradually increase the size until performance drops, and then go back to the last size that worked well. This will be your maximum.
Note: Setting up a course somewhere else, or when things that add "drag" to the course change (using a critter lure instead of a compostable flag, cutting the grass, etc.) you may have to adjust the course size to compensate for these changes.
TIP: every time you make adjustments, be sure to test the drive to make sure it's working without the line attached before testing the course. The Chase drive will continue to act up and refuse to run properly once it's been overtaxed. Power cycle the drive after any time it acts up. Unplug the drive for at least 30 seconds (up to 2 or 3 minutes) and you may also need to press the reset button to get the blue light on the bottom of the device to blink again, indicating it is getting power and has reset from overtaxing or sleep.