Singer sewing machine--bottom thread bunching--how to fix.

https://video.search.yahoo.com/yhs/search?fr=yhs-adk-adk_sbnt&hsimp=yhs-adk_sbnt&hspart=adk&p=Singer+sewing+machine+how+to+adjust+tension+looping+lower+thread+youtube#id=6&vid=5997b793372a18950abb78717c74601a&action=view This is really useful and both my new and old model had this stitch problem. I try to do what he just did, and sometimes it works, this morning got worse. Well, have to adjust again. Usually I adjust the bottom and then the top-- In case of old one, I had it heavy use abt 20+ years, never oiled and bottom could not be opened, finally I opened it, lot of lint, 20 years worth in there, plus a needle that fell in, and I was able to fix, using cooking oil. These machines don't give you enough screwdrivers etc. Finally, old model--feeder dogs fell in, and I would need a long-handled screw driver to fix, and could not find a mechanic though asked around, so ordered this model, which had same problem, fixed and dared not touch, but somehow happening again. Last night had to watch Summit live 8 PM, and at 7.50 I cursed sewing machine, "If you don't work, I will stop sewing," and it made a straight stitch, wh I had no time to check due to live TV, wh only showed motorcade going along, and outside of building in Sentosa with the very fat woman, maybe in charge of press corps. I liked her black and white dress, but she was so large, sorry to say, pattern was like a cow, but she was very pretty. Maybe she should have chosen an ombre pastel floral in soft fabric. This morning I checked back of stitch/cloth, and in adjusting, made it worse, many times opening bottom, laying machine on side to put bottom back in. Now much much worse, big loops and jamming, but I am going to put on my sweater, air con too cold, brush my teeth and try again. What a life. Plus I had to vaccuum around the machine and my chair as so much black thread on floor. FYI, I have been making my own clothes,probably 00s of dollars worth,since I was about 11 or 12, and have done FOUR craft shows, including a trunk show with live models, and sold wearable art and knit scarves, and I keep sewing because I can, and this machine has a self-threader though eyes are a challenge. Now I don't know whether I should bless or curse the machine. kmkaung 6-12-2018