Hi , I have a Bushnell 570 x 60 Rotary Compact Reflector Model 78-9570 and both rack and pinion focusing knobs have broken off - the alloy(?) has broken about 1/2" from the black knob. Is it worth repairing ? Thanks, Steve

There is a simple gear inside -- take the bottom plate off the focuser and see if they are engaged or broken.

If a gear is broken you will need to buy a new focuser.

Put the eyepiece into the focuser and TURN THE FOCUSER KNOB!

You never told us what model number or telescope TYPE you own. Is this a refractor or a reflector. ???

If a REFRACTOR usually you have a diagonal, the diagonal goes into the focuser and then the eyepiece goes into the diagonal.

On a REFLECTOR the eyepiece goes directly into the focuser.

All the manuals for Bushnell telescopes are located on this web site- look down the page for your model telescope:
http://www.opticsplanet.net/bushnell-warranty.html

Put the eyepiece with the LARGEST number written on it into the focuser, this is your lowest magnification.

Take the scope outside during the daytime and practice focusing on a distant object. Turn the focus knob slowly while keeping your eye on the eyepiece, watching closely for a focused image.

Read my TIPS on my profile page.

A repair kit is found here:
http://cgi.ebay.co.uk/Bushnell-Voyager-Focusser-Repair-Kit-Rack-and-Pinion-/150485754340?pt=UK_Telescopes

You can buy a new focuser here:

http://www.telescope.com/control/category/~category_id=focusers

A refractor has a lense in the front, and the eyepieces go into the back.

A reflector has a MIRROR inside.

Here are all the Bushnell manuals about 1/2 way down this page:

http://www.opticsplanet.net/bushnell-warranty.html

It's not worth replacing the focuser on that telescope-- here are replacement focusers of good quality -- notice the prices!

http://www.telescope.com/control/category/~category_id=focusers

Not worth repairing-- a new focuser for your telescope would cost as much or more than the telescope-- unless you can find a discarded telescope of the same model..... for parts.

Yes you can -- several different telescope retailers sell focuser here is one:

http://www.telescope.com/Accessories/Telescope-Focusers/pc/3/51.uts

You must buy the correct size that will fit your tube.