Voltage Regulator

In fact, it is very difficult to find excellent condition of LM323K because there are a lot of pulled and/or counterfeits that cause frustrate for us on S-100 group.

May I suggest you to redesign PCB to use LM323T, TO-220 package before order. Secondly, avoid TO-3 on future boards would be much easy for us.

For old boards that designed with TO-3 can convert to TO-220 by add low-profile heat sink, three 22AWG stranded wires, thermal compound and 3-pin connector and plug into the voltage regulator as much like Heathkit did in the past. This procedure will make easier to replace the voltage regulator quickly compared with soldered-in TO-3. Here is copied from Heathkit assembly manual for IM-2420, 512 MHz Frequency Counter to give you an idea.

Otherwise, if you have something better idea? Please post here..

Thanks,

Steven