Air bed double with slow leak (The Hockering GU22)

‘Best way’ blue air bed. I inherited this so checked it out before putting it on Freegle. Blew it up yesterday (it’s got a built in mains powered air pump they call a ‘Sidewinder’) and 24 hours later it is softer so must have a slow leak. Otherwise seems good condition. Double bed size. Fits in a shopping bag.