nw 6.5 sp 5 srvrs some with edir and the other s edir 8.8.1

On some srvrs imanger is accessible but on others it is not. Doesn't seem
to be any pattern. I used tid 700759 and am about to delete and recreate
the CA object.

Do certificates have to be periodically recreated?

Is it to be expected that I should run pkidiag once a year?

Are there routine maintenance procedures I should run on nw srvrs? The
Health checks?

I also notice that a few of the servers have alternate console screens in
the console screen list. Is this the result of an abend?

Thanks for any help you can give me.