I had two Watts 150a water arrestors installed by my washer a couple years back to prevent water hammer. The water hammer is back and I’m told I can “recharge” the arresters.  There is a bicycle-tire-like valve on the front of each arrestor but I have not been able to find any direction as to how to do so (like How much air do I add? can I do damage if I add too much air?)

Thanks in advance, great site and YouTube channel, I used your videos a lot when drywalling.

Jim