My first try was with silicon lubricant. I went back and tried liquid dish soap with no success. I can get about an inch inserted at most. My rubber strip has a steel insert and is not flexible. This prevents you from sliding the insert straight in. You can get things started but the slight angle of the insert to the bar prevents you from continuing the slide in.

My thought is to remove the inner edge of the insert groove so that it will lay or press into the channel. I can then secure it with adhesive or a bonding agent.

Any thoughts? Am I still missing something?

Thanks for your help.