Reviving a 6 year old Epson 7600

This machine was used briefly when first purchased. It was loaded with full-size cartridges that are still full. The owners was negligent with upkeep. The printer has now two main issues: 1) cartridges are locked in and will not release. Read somewhere that there is an internal spring that when snaped off will lock cartridges. Front screw to take off the lock button slider is not accessible because of large cartridges. 2) print heads totally clogged. Tried test nozzle test and it prints blanks.
Would like to know the best way to proceed in order to find out if its worth time and expense in bringing it back to life.

I bought a dis-used 9600 once. It’s the larger version of the 7600. It took had stuck cartridges. I was able to free them up using manual brute force and they’ve never stuck since. Just wobble them up and down slightly as you pull hard and they’ll eventually come loose. There is a spring clip holding them in, and apparently with disuse, become ‘stuck’ to the plastic cartridge. Force was all I needed; and don’t be afraid of breaking anything. See other posts about how to clean the heads, I had to remove mine and soak it in cleaner (piezo cleaner and/or windex).

THANKS, will give it a try.