To truly diagnose this you should have a multimeter to check the resistance of the coil. A good digital multimeter is a vapers best friend in times like this. I set mine to 0-200 ohm/beep, red lead to center hole of
threaded end, black lead to outer threads. A Joye 510 atty if healthy should read 2.2-2.6 ohms. If it is a lot higher than this, like 3.0 ohms or more, then this could be a sign of a dying atty. A healthy atty should glow
brightly on either side of the bridge...like a pair of eyes with a bridge nose in the middle.
But even a higher resistance atty should glow some, so I am leaning towards your wick is completely gunked up with crud, and blocking visual of the coil glow. Your statement of bad taste but still vaping supports this. Cleaning this out well needs care. I have great luck with polydent overnight tablets. Put atty in maybe 50 mL of hot water, add tablet, swirl occasionally and let it soak for 12 hours, then flush with hot water by using the atty like a straw and
gently pulling and pushing water through it. Shake it out good, then dry in a 200 deg oven for 30 minutes, or else leave it out to air dry for a couple days if there is no hurry. Brings the majority of my yucky clogged attys back to very close to new condition.
Good luck!