I have this one and it has no leaks whatsoever! Hughes treated my Blacklight Dual Color Wave Machine real well so when I took it with me to the school lock-in, it had no leaks. Plus there are bubbles sticking on the uv pink waves, and the uv yellow/green liquid on the top has a small air bubble now which hides in the black ends until it moves again.
I used to make wave bottles for my friends when I was a kid. I used paint thinner for part of the fill and added Johnson and Johnson baby oil for the other half. They worked flawlessly. I just cannot remember 100 percent if it was the thinner I dyed or the oil blue to create the blue wave. I think it was the paint thinner. Not sure if the oil would take the dye. Either way they worked very well and never leaked or smelled once sealed. As for sealing the leak on your lamp it's impossible once it starts. . I had several of these and sold them once I noticed the liquid dissipating. I could not remove the end caps. And when I messed with the microscopic crack it got worse. I actually had to throw one away it got so bad. Acrylic nail polish just helped to open the crack more and I not water proof. I have no idea what to use to seal it and silicone will not do the trick alone. I think epoxy glue which is water proof would do the trick. The kind where you have to mix the two tubes of glue then apply before it dries in 20 or so seconds. I use it to seal my Grande lamps and it works very well. Maybe Gorilla Glue?