I started learning the oboe when I was 10, and went up to get a distinction at Grade 8 in the UK. However, my lips were nearly always sore, and I realise now that my teeth were biting in to my lip. I am now 44, and finding it very difficult to imagine/feel how my embouchure should be with a reed, regardless of reading articles. Any ideas/help greatly appreciated! Cass
A retraining with exercises involving the "set - relax - air - jaw-pressure" type routines might be in order. https://www.somsd.k12.nj.us/site/handlers/filedownload.ashx?moduleinstanceid=4175&dataid=13286&FileName=Basic%20Bassoon%20Articulations.pdf shows a good example of training the embouchure to not need to work while as much so the jaw pressure will increase enough to stop vibrating the reed, instead of the player clamping down. Air-articulations are practiced before tongued articulations.
The following could be done to train the embouchure not to squeeze down when switching from the relaxed lips/calibrated jaw pressure "heh" syllables to the tongued "teh".
X:2 T:Exercise 1 M:4/4 L:1/8 K:G | "heh"G "heh"G "teh"G "teh"G "teh"G4 | G/"etc"G/G/G/
The fact that you've been biting means you haven't developed the muscles in your cheeks. You'll have to start using much softer reeds, and progressively use harder reeds to build the cheek muscles up over time. If you try using too hard reeds you'll just fall back on your old technique.
Also keep in mind that since you're in your 40's now this will take more consistence, persistence and time than for a teenager, since muscle growth overall slows with age.
You need a teacher or another professional player to help you determine the quality of your embouchure. If you know what it's supposed to look like, you can also use a mirror (I personally always start my practice sessions next to a mirror to make sure everything's dandy).
It's common for reed woodwind players to have lip problems, some even develop calluses (still better than the split lips some trumpet players get). I would recommend (as have others) to start with very soft reeds and limit your practice sessions to 2x25 minutes a day. If you feel pain, you should stop for 1-2 days until the lip heals. I did some research before I started playing a reed instrument, and, as far as I remember, there's even some solutions in the form of gumshields and whatnot. You could probably consult your dentist and order a thing they use for people who suffer from bruxism (teeth grinding when sleeping), but those are quite expensive (about 400 USD). A dentist would also be able to help you determine any issues with your tissues and help you overcome them. If you are a smoker or an ex-smoker, you are likely to have problems with blood flow to your gums and lips. Bruxism and other dental issues can make your teeth chipped as well. That's why I recommend seeing a dentist, an orthodontist and a dental hygienist if you have any concerns.
With the mirror exercise, you could do what many aspiring flautists do. Turn on a tuner, form the embouchure with the instrument, look in the mirror, play a note, look at the tuner, remove the instrument from your mouth. If the note was off, try again with adjustments until it sounds right. Continue taking it in and removing it until you can form the correct embouchure. Moving the instrument away from your lips will help you determine the correct positioning and train you to replicate it. Just make sure you are consistent and don't forget to look at the tuner.
You should always be conscious of your embouchure when playing, especially in the upper register, and the tuner is your best friend. Try to always have it on when you practise and do not play by ear, at least when you start out.
Another good exercise that I personally do is replicating the embouchure without the instrument. You can do it on the bus, on the train... you get the gist. If you have to take a break from the instrument because of lip pains, that's an exercise that you can do as well.