Got an Ensoniq SQ80 for $100! Sounds very cool, but I’m experiencing some issues that are making it mostly unusable. Need to know if it would be worth the repairs or if I should just look out for another one in better shape 
On power up, it says battery low, so obviously that should be an easy enough fix.
Once loaded up, it runs fine. I can select patches and all buttons function. But…
1- Some of the black keys are triggering aftertouch or modulation (wobbly notes) no matter how light I press them. Also keys are very clacky (which I understand is typical of this unit).
2- I’ll be playing a patch and all of a sudden the synth will basically glitch and be stuck playing a sound that is totally different than what was selected, (does like an audible spaz attack) and the whole system is frozen up. Have to restart.
3- Sometimes I’ll be playing a patch and all of a sudden the sound will cut completely out and the whole system will be frozen up. Have to restart.
This isn’t intermittent- it basically occurs every time within a couple minutes of powering the synth up and playing it. Unfortunately, the freezes and spaz out’s are making it impossible to use the synth. Am I way out of my league here?