Post #2 was a correct answer to your fuel leakage problem.
Your 2nd Q showed that unfortunately you do not understand even the very basics of how an internal combustion engine works.
Without that basic knowledge, there is no point in trying to type a post that will help you, hence the advice to either do some research,(reading), or find a marine shop to do the work.
Your compression Q is akin to saying, “ I have a flat tire, could this problem be why my air conditioning doesn’t cool?”
There is wealth of people here, each with dozens of years hands on experience. If they tell you to learn the basics first, you should do that.
A non mechanical analogy might be you are wanting to study the founding of your Country, but cannot read.
You would be advised to first become literate, without that basic start, no one could help you.
As suggested, a few hours of reading & Youtube would be of immense value. Even if it results in deciding the work is beyond your skill level, at least one might have some understanding of what the shop technician tells you.