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Need more information- several Meade scopes have a flip mirror like the ETX 90 for example. Usually it is in the position to use with an eyepiece. However it can be flipped so the rear port can be used on the telescope.
Hope that helps. There is a known issue with these old flip mirrors- the adhesive holding the mirror can fail. You must disassemble the scope and apply new adhesive to hold the mirror in place.
Confirm that the lens cover has been removed from the telescope.
Confirm that the flip-mirror control (16, Fig. 1) is in the "up" position if using the eyepiece holder (4, Fig. 1) so that light is directed to the eyepiece (1, Fig. 1). Confirm that the flip-mirror control is in the "down" position if using the #932 Erecting Prism or doing photography with the ETX-90EC (see Telescope Controls and PHOTOGRAPHY WITH THE ETX-90EC).
It sounds like you are correct about a mechanical issue with the knob that moves the mirror. If you need a quick fix try your local camera repair or watch repair shop as the are familiar with intricate parts. The camera shop would be preferable as they know optics. Otherwise you could ship it to me and I could repair it fro you depending on the availibility of parts if parts were needed. Check my picture for my site address and get contact info there for more information.
The Meade ETX90 does NOT have small lens! It has a large curved lens in the front. and a holder for the eyepiece in the back (top). There is also a camera port in the back, and a flip lever that sends the light either straight back to a camera, or UP to the eyepiece holder.
There is an INTERNAL secondary mirror mounted on the back of the front large lens. If this fell off INSIDE, you will need to remove the front lens to fix it. NOT an easy fix as the optical alignment can get messed up when you do this.
Here is the manual for an ETX90, you should read it completely.
Not worth fixing a Bushnell telescope. The mirror is attached with CLIPS that tighten down on the edge of the mirror. Look at the bottom of the scope for the mirror clip bolts. DO NOT over tighten these. You should be able to stick a business card between the clip and the mirror. This is tight enough.
The C8 optical tube has a very large focal range. It should be capable of focusing on objects from 15' to infinity. To focus on object at infinity you have to move the primary mirror foward. You do this by rotating the focus knob CCW. Rotate the knob CCW until it comes toa stop them slowly bring the mirror back by rotating the knob CW while viewing the object. It will snap to focus so don't move too fast yor you'll miss it.
The primary mirror of the N4 is very securely held in place. The secondary is an aluminum coating on the back of the meniscus lens and can't move. I think what you are seeing is the secondary mirror's baffle tube becoming misaligned. This can happen if the scope is left in a hot automobile. Contact Celestron support for repair services.
The ETX 80 is very difficult to work on. Getting at the flip mirror requires an almost complete teardown of the telescope and its mount. If you are not experienced at repairing the ETX scopes I would not advise trying this youself. I doubt that leaving the scope in the case too long is the cause of the coating damage. It takes years for fungus to really destroy coatings. I have seen newer Meade mirrors losing their coatings prematurely and feel this is a manufacturing defect. If the scope is in warranty it should go back to Meade. If not I'd have my dealer look at it and see if Meae will make an adjustment on it.