One of our members recently made me aware that rubber tips for the VIA phone mounts are available on Amazon. I'm not suggesting you buy them ... just wanted to let me know you can because so many buses are missing some or all of them. The company should be buying these by the hundreds but it's up to you.
Four for $7.49 or 8 for $8.97. You can split it with someone else who needs them. Search Amazon for "Ram Mounts Rubber Tips."
They also have the tool for tightening the knob. Search "Ram Mount Security Knob."