Thanks guys.
continuing:
I switched to driving the IRL520 MOSFET. This works great. Solenoid engages when all inputs to the 4012 are tied to 12 volts.
Problem is, the NAND gate is burning out (or something?) After a short time, pulling the inputs high (to 12vdc which is what VDD to the chip is) the ouput of the NAND no longer goes to 0 vdc, but 6-7vdc.
I pull the inputs low through a 47k resistor, and pull them high, directly taking them to 12 volts. Any ideas?