G'day and welcome to the forum
. I really appreciate your honesty and also your desperation too.
No, this is something I don't feel you should quit. In fact I reckon nutting this issue out will be incredibly significant for you. And haha do not get surgery for this
, and monetary reward, I wouldn't recommend hehe but I appreciate your willingness to want to see this issue through!
I also struggle with incredible tension issues, manifesting as a severe pelvic tension issue that I've endured the last 3 years almost. Also upper body tension within my own karate practice too, so I can very much relate to this. It's been a work in progress for me, and still is, but I've come a really long way and my technique is dramatically different and more relaxed and free nowadays.
It will not happen instantaeously. Some thoughts:
Either a) your sensei just thinks you're tense but perhaps your structure/movement just looks in a way that suggests it's tense, but really is not. Or b) there really are unconscious tension issues.
If the tension really is there, a few things come to mind... is it possible you're trying too hard to relax? Relaxation comes through letting go of excess concern. When you fill your technique with excessive ambition, that is, being overly concerned with the 'shape', form and perrrrfect technique, it can really hike up into your upper body and manifest as tension. It's like an over-concerned seriousness that is filled with solarplexus driven ambition, and it can really stifle the natural flow of technique.
Sometimes this is deeply psychological and many including myself will tense when being watched, ESPECIALLY when your instructor is watching you directly. There can be an inherent need to please, get approval from, impress, show that you're strong etc, and perhaps the constant commentary that you need to relax is actually gnawing at you as you feel like you're being MORE watched than ever before, hence tensing to TRY HARD to relax.
I'm not sure if you struggle with this (tensing when feeling like you're being watched), but this is deeply psychological and you'll need to look into any core beliefs you have hanging around within yourself, whether it's related to fearing authority figures, needing approval, needing to 'appear strong' but really coming from an insecure place etc. The body does not lie, and tensions show up in response to how you hold yourself, which filter through core beliefs.
I'm being direct and honest about this as I can sense your desperation.
Another thing is I noticed in your original post you wanted EXACT, PRECISE, SPECIFIC detail. This to me shows a little (or maybe more) perfectionism... and I think this may speak to the core of it...
I may be very off the mark, but these are just some thoughts that I hope are helpful in some way.
I came from a very very hard style of karate, and I had/have to unlearn a LOT of tension patterns, so I feel your struggle man.
Another thing, I'd recommend stop comparing yourself to others bro! It'll just eat away at you in so many ways. We're all on our own individual, unique journeys and paths, this is yours. Own it, and see the gold that's in it for you. Doesn't matter if others have 'got it'. Chances are you've got great things others don't too!
But seriously, with all this stuff, one... step... at a time. Take a really nice deep breath. Like you've just walked for 1000 years straight, and finally get to take a load off and sit down. That sort of breath. Sink into that feeling of relaxation and learn to be with it. It may take time, but it will absolutely, without a doubt, be time incredibly well spent.