Of course, a Piggyback Z8 is less reliable than a Mask ROM part. You have 24 extra connections that can lead to errors, and the whole thing is heavier and could come loose from the socket during transport. IC sockets and Apple - this is a very special story. It's a good idea to remove each chip from its socket once every ten years or so and put it back in. This will eliminate many problems associated with contact corrosion.
- Is the Z8 one that can be used for LLF?
- is the Z8 on this Profile one I should replace?
Yes, you can use it to format. And if you want, you can upgrade to FW 3.98.
There are not many things that can replace your Z8. If you have a mask ROM version, use that and keep the Z8 for formatting purposes. Otherwise, your only alternatives are the Z8 piggyback or an UB8820M piggyback board.
With 0x1C = 30 used spares you still have two left. You could format your drive (luckily you own a piggyback Z8 ;-) and see what happens. If the bad blocks come back, there is a media error. That could be from a head crash, if the drive was moved while the disk was spinning. If they stay away, they are from loose contacts on the logic board, a weak power supply, or a user in a hurry who turned off their drive before it finished all operations. You can perform low-level formatting as many times as you want, and nothing will break if this process is interrupted in any way. You would just have to start it from the beginning again.
