Bought new 7006SB receiver to convert one of my old 72Mhz planes over to Futaba 2.4Ghz 14SG system and the servos are chattering but they do work. Have it programmed for Mode A and FASSTest. Has S148 servos and all worked good using the 72Mhz system. Any ideas?

Make sure the transmitter is in 14-channel FASSTest and not 12-channel FASSTest

If you are not using telemetry you can try setting the RX abd TZ to FASST instead of FASSTest as well.