Porter-Cable - 10" Table Saw Model: 270TS (Rating: 5)

I have owned this saw for almost two years. I am going to retire in a little over a year and I have been setting up my workshop with tools that I feel I will need at that time. I haven't been able to work down there very much but have done some work there. My question is the height adjustment. It won't go down. It is in the up position now but won't move. It has been this way ever since I have had it but didn't do any thing with because I didn't have the time. Now that I went down to change the blade it came with to a 80 tooth blade, I started looking at what the problem was to make it inoperative and found that the screw just turns in the housing and nothing moves. I was hoping that it was just going to be a simple adjustment but I found that this isn't the case. I noticed that the lock nut isn't tightened to any thing. Before I get too far into it, does anyone have any idea what I should do? Hopefully I just have to tightened the up the lock nut but at what end of the shaft? I love this saw as it cuts just about as good as my son's unisaw, if that can be believed. Thank you for any help that anyone can give me.