I recently bought an excellent condition Morse 4300 off Craigslist for $70. I couldn't find a free manual for it, but a manual for the 4400 exists for free online and I used that to help me locate all the lube points. After lubing and greasing it up, it runs great mechanically.
I am having issues with the quality of the stitch though. It seems that I cannot get the the stitch to look even for more than a few inches at the most. Basically, what happens is that for a few stitches, the stitch will be buried between the material as desired, then a stitch or two will pop through the top, after a few more stitches, the stitch will pop through the bottom. Furthermore, I'm seeing individual strands of the thread unraveling during sewing. I have attached a picture of what I'm talking about here. Stitch length is set to 6 stitches per inch (the longest possible) and these problems occur in both straight and zig zag stitch settings. One thing worth mentioning is that when I sew through a thick vinyl, I get perfect, consistent stitches.
I'm using Gutermann TERA 40 100% Polyester thread and Schmetz universal 100/16 needles and am sewing on 1000D nylon Cordura. I have used this combination in another machine and haven't had these issues. I have rethreaded the machine several times (I followed
this video. I tried going through both guide holes and just one guide hole on separate occasions), wound multiple bobbins slowly and carefully, and adjusted the bobbin case with the "drop test" (even loosening and tightening from this setting and adjusted the top tension to match).
I'm at a loss. Is this a tension issue? A timing issue? Is the inconsistent tension issue related to the unraveling strands issue? Other than these issues, I really love this machine and am eager to get these problems fixed! Thank you!