I recently bought an old (1988) BF5 planer/thicknesser with mortising attachment. It is in very good condition and I am wondering if being so old fitting a helical head would be overcapitalising it?

I am also after a manual and any maintenance program I should be observing. Everything runs well, very quiet and nicely balanced so I assume nothing urgently needs attention but I don't know its history so any suggestions are welcome.

Thanks in advance Craig