My brother and I both bought our first REOS in early 2011 and he still has his. He has never even bought a back up. It's his one and only mod and he has been vaping for over 6 years.
I sold mine to buy a ProVari years ago, which was dumb. I've since bought about 10 REOS. I'm now down to 5 and...
Maybe take the atty off and the bottle and hose off and push a straightened out paper clip up through the juice nipple into the 510 to clear out a possible blockage?
+1 on Deoxit Gold. I use it every few weeks on the firing pin, spring, spring screw, battery tops and both terminals of battery charger. My 5 REOS all hit like a beast.