if your going to seal with silicone tape, its that thin stretchy stuff for plumbers
you can seal it in 2 places to test it out
one is at the bottom base on the screw portion, so when you apply the tube on it the seal will be made and juice cant escape, just like plumbers would do, oyu tape around the bottom connector then the tube screws over that.
the second place you can try a small peace would be under the cup where it connects to the tube.
you need a inner plug or else you wont be able to tilt it, to make sure that section is good, remove the inner plug, make adjustments to it like some do by enlargening the slits in the plug, not needed but some do this.
then alling the slots or with the slits on the cup and press it on firmly so there isnt a huge gap for juice to enter,also do this while its screwed onto your battery so as to not push the pin through the connector.