I had an old Multico one, was different to most I have seen as the bars that the sliding carriage ran on were one above the other instead of side by side which seems the norm.
Could never get it set up properly, it always introduced a slight twist to the tenons, think something might have been broken on it and badly repaired.
I wasted money on it buying new cutter heads and fitting electric brakes to bring it up to regs, was glad to see the back of it.