First, The FR-300 was discontinued effective March 20th,2018. Replacement/repair parts are only guaranteed for 3 years. And we are already 18 months into that 3 year guarantee.
I just bought a couple of extra nozzles. I may buy a new heating element, too.
Once these parts are gone your FR-300 will be junk if you have no replacement parts.
The replacement for the FR-300 is the FR-301. Parts will not interchange.
Spare parts or the FR-300
Second, I bought my Hakko as a refurbished unit. It did not come with instructions. What I learned is that you are suppose to wet sponge the nozzle just as you sponge a soldering tip. You are also supposed to sponge and add a dab of solder to the nozzle as you would a solder tip. Doing these two items sure did help with my desolder task.
If you already knew this---BRAVO. If you did not know, give it a try on your next desolder job. You will be glad you did.
My Hakko seemed to be slowing down in the vacuuming-the-solder-away department. I replaced my filters regularly and made sure my nozzles were clean but the vacuum action was substandard. Here is why:
The clear vacuum tube located under the yellow cover was clogged with solder. I don't know how the solder gets past the ceramic filter but it does. So, if your your solder vacuum seems lackluster, check this tube. If it is full of solder, unplug it from your gun and run a small nail or drill bit through it to clean it out. Replace. And your vacuum action will improve tremendously.