I flush 'em with WD40. No disassembly required, unless you are brave and adventurous.

Sometimes it takes as much as a half a can, over several days (which seems like a lot; squirt-shift, squirt-shift, wipe down, turn bike upside down, squirt-shift, repeat ad nauseam), but each of the three sets of brifters I've owned (600 Tricolor 8-speed, 105 8-speed, and RSX 7 speed) were gummed up and nonfunctional when I got them, and all work fine now. After they are working free, I squirt some white lithium grease spray (chain lube) into them. Not sure if this is recommended by the experts, but I didn't want to try and take them apart to put whatever is correct back in there.

Also, you've probably figured out the bike is actually a Novara, and auto-correct is not your friend here