HP Laserjet 4 Plus printer (Marlow SL7)

You would say this is retro or vintage as was made in 1994! Was working till a couple of years ago, now says ‘50 Sevice’ when switched on. It’s a fantastic b and w laser printer, you get thousands of clear pages from a toner unit. Wondering if anyone is up for making use of this by repairing or for spares. Thanks, Sally