Weak spark , won’t start.

Hi Everyone. I recently finished a restoration of my KZ750B4. Have had a few short rides and was running reasonably well.
Tried to start last week but sounded like misfire or randomly fire. Nothing’s changed since last ride , however when checking spark it looked very weak. Thin blue spark. I would still think that would be enough to start but donesnt want to fire up.
I’ve carried out static resistance checks on coil, regulator, stator etc and all seem to be ok, however I understand this doesn’t rule out other issues that might be found if it was running.. Plugs are wet so no problem with fuel.
Can anyone suggest anything I might be missing. I’m f@##in frustrated!

Load test the battery. A weak one can show more than 12v with no load but still not have enough power to start the bike. Also check both ends of the battery cables to be sure the connections are clean and tight.

In addition it's always good to verify all the basics: points condition and gap, valve adjust, petcock flows properly and tank vents, spark plug cap condition and connection to the HT leads, air filter condition, etc.