If you silicone the hole make sure you put a small amount on your finger and spread it in the hole wall no more than a 1/16 thick or less.Too much and the tube will push the extra down into the trans and could stop something up.I would check the o-ring and tube for cracks or if its out of round first then silicone if that doesnt fix it.If you silicone the tube you can put it on your finger and run it around the tube much like caulking in a house and it won't be noticeable.