Hi everyone, thanks so much for your advice! I thought I had posted reply but it looks like I didn't do it properly....so trying again.
Lady Diana - I was very lucky to get the machine with both original manuals so I followed the threading/tension instructions to a T. Sadly the stitches were still pulling and that's when I tried on paper to try to eliminate the thread and tension possibilities.
Gymnast2 - If I understand your diagram correctly, I think my machine was doing the opposite...when I looked very closely, I saw that the feed dog was at its highest just as the needle was clearing the plate.
Since Janey had kindly provided me with links to 62C service manuals, I found instructions to adjust the feed dog timing and decided to gave it a go. Several long hours later with a lot of nervous perspiration and unlady-like language
, success! The machine sews beautifully now and the special cam stitches are coming out as they should (love the ducky stitch).
In hindsight, it was a very simple adjustment once I found the right tools, but because this was a 'bigger' adjustment I've ever made and I didn't want to do more damage to the machine, it was a bit nerve-racking, lol.
I think I'll still take it in to a pro for a full servicing so that I can experience the 62C in all its vintage glory. Thank you all for helping out this newbie!