Thank you all for all your suggestions. After a good night sleep, I decided to give my machine one last cleaning before it goes off to the shop. I took off the cover to check and clean my upper tension again. This time, I followed my thread as it went through all the twist and turns of threading. I discovered there was a big piece of lint hidden in one of the tension area (not sure how I missed that...lol). Again, I thank you all for coming to my rescue :thumbup:
Tea :D