I found this on a Ping community forum:
Question: I would like to change the swing weight of my i3/i3+/G2/G5/i5/S59 irons, can that be done at home or
would they have to be sent in? Isn't it just a matter of changing the weight in the back of the club?
Answer: The swing weights of the irons can be adjusted (within certain limitations), and the clubs would need to be sent to us for the adjustment. We do just change the backweight, but we cannot sell them or send them out loose to anyone (we do not have any direct sales to consumers, and we do not sell component parts to anyone). Most repairs are in house about 5-7 business days, plus the shipping time back and forth.
Please use our repair form:
http://www.pinggolf.com/global_repair.html