Toilet Cistern Overflowing Unless Float Manually Lifted

[Phil33]

Not sure if anyone will be able to help me as it looks like I can't add photos (other than via Photobucket etc). My toilet is overflowing unless I manually lift the float. There seems to be friction between the lever and the threaded rod which sets the float height / water level. The valve is similar to this but side rather than bottom entry: [urlhttps://www.lowes.com/pd/KOHLER-Revival-Rialto-San-Raphael-10-in-Toilet-Fill-Valve/1000144753][/url]

I bought a new valve assembly but it is too big to fit in my rather small close coupled tank. It looks like I need to bend the lever slightly so it does not press so hard on the threaded rod but it looks to be brittle plastic which would probably break