Apple Lisa 2/5

Hello,
I got hold of a Lisa 2/5 that has suffered from the usual corrosion on the I/O board. I cleaned it up and now it boots to the self-test screen, however, it sometimes shows error 52 on startup and sometimes it doesn't? I know this error relates to the COP421 chip if that helps, but I don't understand why this error is intermittent. Anyway, when it does boot I get to the floppy screen and can insert a floppy and begin the boot process. This always seems to stall at a certain point and throw out another error. I know the disk is good and the floppy drive has been cleaned. I also get the same issue if I boot off a ProFile. It starts booting and then stops and shows error 10741. The ProFile is also 100% working. I get error 10735 for the floppy disk.
Any ideas,
Max1227
I got hold of a Lisa 2/5 that has suffered from the usual corrosion on the I/O board. I cleaned it up and now it boots to the self-test screen, however, it sometimes shows error 52 on startup and sometimes it doesn't? I know this error relates to the COP421 chip if that helps, but I don't understand why this error is intermittent. Anyway, when it does boot I get to the floppy screen and can insert a floppy and begin the boot process. This always seems to stall at a certain point and throw out another error. I know the disk is good and the floppy drive has been cleaned. I also get the same issue if I boot off a ProFile. It starts booting and then stops and shows error 10741. The ProFile is also 100% working. I get error 10735 for the floppy disk.
Any ideas,
Max1227