Welcome to the forum Dean.  For replying, down at the bottom after the last post, there's a button that says "Add Reply" that will allow you to respond to the thread.  Inside the box around each post there is also a button near the top of the box that says, "Quote", this button will include a copy of what the other person said, and then you can type in your response below the quoted text.

With regard to your vibrato issue, first, I wouldn't put that at the top of "The most important things to be able to do with a violin" list.  However, I think you have hit on the answer to the problem yourself -- You said: "...it's not how I'm holding the violin etc."  I'm guessing that it is, since you go on to say that you can't lower your elbow enough.  So the first thing to do is review how you are holding the violin.  Look over there ==>, on the right sidebar, under Pages and look at the first tutorial on "Holding the violin."  Make sure that you can and do hold the violin as it shows in the video tutorial.  My guess is that you're going to have to adjust the way you are holding the instrument.  Let's go through the physical list of abilities required first.

First, allow you arms to hang naturally against the side of your body.  If you can accomplish this, then your left shoulder is not going to be the problem. 

Second, with your arm hanging near your side bring your forearm up and touch your shoulder with your hand.  If you can do that, the left elbow is probably not the problem.  

Next, try forming a circle by touching the tip of your middle finger to the tip of your thumb.  If you can do that, and the circle is larger than the neck of a violin, then you have plenty of room to get your hand away from the neck for vibrato.

With your hand still forming a circle and pressing the finger tip lightly against the thumb tip, straighten your thumb and watch the first knuckle of your middle finger move, then move it back to form a circle again.  Do the same with each finger.  If each knuckle moves without pain, then you have the necessary finger flexibility to do vibrato.  

Hold your hand up and move it from side to side and forward and backward, if you can do this without much pain, then you have the wrist flexibility to do vibrato.

If you can do all of the things above, the issue is simply one of learning the proper technique, not one of physical ability.  Vibrato is not easy.  Do not expect it to be learned quickly, but if you do it with improper technique, expect it to take forever. 

I'm 64 and there are folks here in their 70's. Most of that crowd, and me included, have pretty creaky joints. Welcome to the arthritic, but still rockin' group.