higear double inflatable mattress (may have a slow puncture) (Dane Mead RG24)

I was going to take this to the tip but wondered if anyone would be prepared to fix it as we think it might have a slow puncture. We inflated it last weekend and it deflated slowly overnight. It’s a higear brand double size inflatable mattress with a flocked top. A bit dusty in places but would be worth a go if you could find and repair the puncture. Can leave it in our front porch for collection- needs to be collected this weekend