About Defenders at Fortress War

[Aryss]

Recently my union got the fortress everything is going smooth and we just have one doubt about how to repair the gates(and eventually the heart) in the fortress time.

we heard we need to 'hammer' them from inside and that the repair hamers have a cool-down but we still dont know exactly how it works.

can someone with experience as defender explain me in detail what to do to keep the gates healed?

thx for the attention