toilet overflow

Back again. I had some great help with my last post "Adapting Well Bottom cistern flush, not replacing" but I could do with a little more help ( thought it rude to bump an old thread so here's a new one). The overflow from the cistern is 15mm running just off horizontal out of the back wall...

Hi all, My toilet is constantly running (not a lot - but it means that every couple of hours the cistern noisily refills which is disturbing us during the night). There's a front panel which gives me access to the cistern but, I can't get in to the top of the cistern in order to change...

My toilet has started to overfill. Anyone know how I adjust it? It fills up then keeps going for about 5 minutes. I can see it overflowing into the toilet bowl.