There was never a recall issued by Keystone on the "popping noise from autolevel system". Lippert, to my knowledge also never issued a recall (for all units with the system installed). Rather it was a "service advisory bulletin" issued by Lippert which stated "IF" the system develops a "popping noise" to add one quart of "fork oil" to the system.
You can read about Lippert's response and forum members experiences in this thread:
http://www.keystoneforums.com/forums...hlight=popping Specifically, read the information provided by BobBecky in post #5 of that thread. It's almost "ancient history" now as the Lippert action was from 2013 and the thread on this forum was from 2015.
Hopefully this will fix your popping issue, if not, then you might want to have the system inspected by your dealer. There may be something else causing your particular system popping.
Good Luck