If copper has started to corrode, can it stop?
The previous answers doesn't take into account the environment: 


  They were operated in conditions of intense humidity/heat and were placed near the sea.


Near the sea means that there are certainly a lot of $\ce{Cl-}$ ions in your metal. Chloride ions are a very dangerous species for metals conservation they tends to depassivate the metal forming complex ions. In the case of copper occurs this series of reactions:
$$\ce{Cu^{+} + Cl^{-} &lt;=&gt; CuCl}$$

$$\ce{Cu^{+} + 2Cl^{-} &lt;=&gt; CuCl2- + Cl- &lt;=&gt; CuCl3^{2-} + Cl- &lt;=&gt;CuCl4^{3-} }$$

That lead to different copper corrosion product. (e.g. atacamite $\ce{Cu2(OH)3Cl}$, malachite $\ce{CuCO3.Cu(OH)2}$ (Did you see some blue-green pigment?), Cupric hydroxide $\ce{Cu(OH)2}$.

These are all dynamic equilibria so your copper with dry-wet, hot-cold cycle will continuously object of degradation until chloride ions are present.

Use distilled water with cotton to clean the salts deposit, dry quickly where you clean.  

Reference:


The Open Corrosion Journal, 2009, 2, 71-76
Corrosion Science 46 (2004) 109–135