You can make these as easy or as hard as you like. Not sure if they'll aggravate your problem, though.
I'm not saying drop the bench dips, but when I first started lifting I did a lot of those and they tore up my shoulders and did nothing for my arms. If you're okay doing close grip bench, you might want to just do more of those and it's variations. Look into J-Presses (my favorite triceps exercise).
Between close grip bench, J-Presses, dips and pushdowns, you should be able to make some gains without extensions. Good luck!