Please don't use vaseline. It may attack the seal.

Don, clean the seals and surfaces. Use the silicone plumber's seal.

These are designed to be screwed down snuggly, NOT tightly. If you used a screwdriver, it's likely WAY too tight and it's possible to crack the acrylic. The screws must be adjusted evenly - or it will definately leak. Remember, this is a VERY low pressure system.