Model Forum / General / Models / March 2008

I've got a Myford ML7 Tri-Leva which over the past few months has developed a
"knock" and I wonder if anyone can offer some advice.  

I recently changed the rather old drive belts as I thought that they may have
worn unevenly, but that didn't fix anything.  After much prodding, I've come
to the conclusion that the cone pulley block on the headstock is loose and at
a certain point in a revolution it jumps from one position to another, so
causing a knock when running at speed.  There is a grub screw on the centre
pulley, but adjusting that doesn't seem to make much difference.

Is this a problem that anyone is familiar with?

My next attempt at fixing this is to remove the pulley block from the shaft
and see if it is fixable in any way or whether it needs replacing, however
that's not a totally straightforward process as there is a tight bush that
needs a puller to remove.  So, before I do that, I thought I'd see if there
is some wise person out there who has seen this before.

Thanks,
John