A picture of the robot in question would help us out a lot. I have built the exact same H-drive from the Vex Drive in a Day kit. It could barely even drive on linoleum or another hard surface. Driving on carpet was much more successful, but there's a large chance you'll still run into consistency issues. Now, you have a couple options open to you.
- Leave it as is. When you get to competition, you might be able to strafe; you might not.
- Take out the strafing module entirely. Then you'll just have a four wheel omni.
- Take out the strafing module and switch out your back two wheels for traction wheels.
- Lower the mounting point for the strafing module. You can do this in a variety of ways, from complex as welding the module to the current drive rails to as simple as getting clever with washer placement. This will mean there is more of the robot's weight on the strafing wheel, allowing you to actually strafe. However, this takes normal force off of your four main drive wheels. This means you'll have less traction when driving forwards, and your chassis may not sit flat on the ground.
- You can design and use some sort of actuating module like the VersaDrop or something completely custom to lower the strafing wheel when you need to strafe and raise it when you drive normally.
- You can design something like 148's actuating modules that use the the friction of the gearbox to provide downforce on the strafing wheel.
Those options are listed in rough order of difficulty. You and your team will have to decide which option is best for you.