We have a toilet which is hung onto a unit so the mechanism is concealed under a timber worktop. The toilet flushes by using a push button mounted on the front of the unit. The flush was never very powerful put now it’s gone pathetic- you have to push it 4 or 5 times and until it builds up enough water to actually flush. Do you think we need a new flush installed? We’d like to check the cistern ourselves but have no idea how to remove the worktop without causing damage.