Online Community of Zenith Builders and Flyers
Don't know if this would help you but years ago I installed nylon (UHMW), wear strips on the V notches and noticed an improvement on my 701. The strips just snapped on the notches and were purchased from MSC Industrial Supply part number 52434073. In order to make them stay in place after cutting to length I had to cut most of the way through the bottom of the strip so that they would easily stay bent in the aluminum V shape. No more messy grease. Hopefully the link works. While you only need a foot, you must buy ten feet for $13.73. The two pieces I installed still look good after 80 hours of use. It is the one on the far left in the MSC link below.
Sorry but I finally found a drawing of the style of V block you have and I'm afraid my suggestion will not help you as my 701's nose gear centering design is completely different than yours.
With your design, find a way to support the nose off the ground such that you could grab the nose wheel and turn it full right and left while observing the action of your bearing surface / crossbar interaction. You already have a spring essentially with the bungy cord pulling down. Now, how could you improve the slipperiness of it's action? Perhaps others with a 601 could chime in??