If quads are a weak point, make paused hack squats your new BFF. I wish I'd done these in the years I was powerlifting when I kept having quad strain after quad strain.
Paused Hack Squat
Unlike barbell pause squats where you can sort of sit down on your hamstrings and unload just a bit, with the paused hack squats the quads essentially have to keep you suspended in a very intense isometric contraction at the bottom.
There's zero unloading of the weight, especially if you don't cheat and let the apparatus rest on the safety stops. Your vastus medialis will be screaming for mercy.
The other great part about including these is that if your deadlift is weak off the floor, the improved quad mass and strength should fix that as well.
Hacks will also give your hips and lower back a little bit of a break as well. A lot of lifters don't realize just how overworked those areas can get when squatting and deadlifting every week. How many times have you heard a guy say he took a layoff, only to come back in and deadlift or squat some new PR?
Fatigue in those muscle groups is a primary reason why someone can't get past a certain weight, or is suffering from too many poor workouts in a row. So don't sweat taking a break from barbell squatting for 8-12 weeks. You're still working the quads and the posterior chain will still get hammered on back and deadlift day.