In the spirit of providing some ideas-
Regarding the battery, SO many times the voltage will read fine, until it gets a load on it. It's needs to be measured with a load on it, or better yet, swapped for a known good battery. Low batteries will generally run in "limp" mode if the engine is running when they go low. This limp mode is most often diagnosed as a carb issue - because that's just what it acts like. It will run at low throttle settings, but then start acting up at higher rpm/throttle settings.
Reed valves are rarely ever an issue, unless they are the issue. Problems/symptoms will be low compression and hard starting...... If they start easily, there's nothing wrong with the reed valves.
On inspection, if there is an issue, it will nearly always be obvious. Hanging slightly open is typical and NOT an issue. Cracked, chipped, pieces missing and a piece of crap lodged under one of them holding it open (yes that happens!) are the most common issues, IF there is a reed valve issue.
Most often, an engine with low compression will start OK when using an electric starter, but engines that are lean on the low speed can be a nightmare to start too, but then run fine. A hair richer on the low can make a huge difference in how easily the engine starts.
My carb issues, if there were a most common one, are nearly always traced directly to that clear build up that the internal screens seem to collect - like metal to a magnet - only this clear crap is near invisible until you remove that screen. From there it's a feed issue. Stubborn ones generally get an entire new/different system from carb to clunk.
Hopefully, something there will jog your brain.... -Al