Hi,
I changed the needle back support bearing to two high quality 6x10x3 mm ball bearings + a spacer to fill the gap in the plastic case. The spacer I used is a centre ring from an APC propeller. The spacer is 9.5D x2.5 mm and with one round of plastic tape it fits perfectly. The fibre glass plate I am using is 2 mm so this adds up to a perfect fit. After installation i have zero play in the back support.
Are these type and size of bearing capable of handling the axial loads which could be generated in some maneuvers.