Constabulary

The Seiko TE-6 head section is pretty much the same as on my former Singer 34K5 (Singer 16 type so to say) which I have restore and later it had an accident and I had to replace the needle bar. I have used a Singer 17 needle bar which is the same as the Seiko and it worked. I used 135x17 needles though the shank is thicker as on Singer 16 needles - it just worked with the new needle bar back then. Just my experience but I no longer have this machine I have replaced it with the Singer 51w. I would simply try a different needle and adjust the needle bar height. Just hand crank it and see what it does. https://leatherworker.net/forum/topic/66729-singer-needle-bar-i-could-use-some-help/#findComment-434368

Google: https://www.google.com/search?client=firefox-b-d&q=needle+singer+51w

ebay: https://www.ebay.de/itm/152425997655

not sure what you mean with needle hook clearance? You mean the distance from the needle to the hook tip? If you mean the rise from the BDC to form a loop then 1/16" is not enough. Machines with 328, 214 or 216 needles usually have a rise of 3.5mm - 4mm from BDC.