Glen my water level had also risen over the years but tit was too high, touching the plastic lid openers on each side . I am brining it down to level with the top of the glass and then I need to move the gate. It is so long since I moved the gate it took a lot of budging cleaning etc.
Just super glad that I didn't have a leak, not really sure what it was but it seems to be sorted.
Its my tank day today so water change , clean and sort out the gate.