lever handle

I have a monobloc mixer tap with 2 levers. The cold tap will no longer grip the cartridge (20 teeth). Tried the hot lever on cold side and worked fine so definitely an issue with tap lever not gripping the cartridge teeth. Does anyone have any advice on how to get it to grip? I had thought I...

The spring has gone on the kitchen door (bog-standard council, cheap) lever handle, but I'm not seeing how to reach the spring to replace it. As you can see from the photo, there's a metal plate inside covering it. It looks welded on and turns with the handle. Does this mean these are...