Rapid fire shifters sticking?

Did a little work on my bro's bike last week. Basically since then his rapidfire shifters are a bit stiff/sticky since then? Just wondering if anyone has any experience with this & what you did to fix it? Before i go stripping them down if it's unnecessary.

Check cables and squirt some GT85 or grease into the shifter?

Did you move the shifters or brake levers? Are they now pressing against each other?This will definitely cause a sticking problem with Deore shifters.
Also had a problem with an old LX today where the grease had dried up and was causing the upshift pawl to stick, working some GT85 onto the offending item seems to have done the job, but needed stripping as just spraying inside wasn't effective.