Years ago I used Rohn Air retracts. I had both firewall mount and belly mount nose uinits. Both would wollow out the pivit block. This was due to a steel strut in a alunimum block. If memory serves me correctly, someone offered a teflon sleve that would isolate the two materials, solving the problem. Has this problem been solved in the new systems that are avaliablei.e. Spring Air? Way am I askingI plan to purchase a new set of gear.