OK, I feel better now.
Lets take it from the top: Breakdowns. How often are these projectors down for those who use them? Right now I've got two down, and both of them just spent a month in the shop 75 miles away in Pittsburgh's South Hills. This just burns me!
Constantly skip: Is there anyway I can adjust the timer on these units so that they do not skip rapidly. I know there's a control on the side, but I'm talking inside the machine. It is so embarassing when customers are in the auditorium and these things start circulating four or five slides in four or five seconds. Any help would be appreciated.
Slides jam half-in-half-out: I think this is coming from the carousel not rotating fast enough. Can anyone ascertain that for sure? Once again an embarassment. I know it can be fixed because many machines that went to the shop had this problem. This particular machine must have been skipped, though. Is there a gear that I need, or what?
Bulbs: This is just a gripe that I have with slide projectors in general. Yea, its OK when you have replacements in the cabinet, but more often than not, we run out right when one of our few advertising customers wants to know why the slides aren't on the screen. I always put in a word to the manager when I only have three to five bulbs left, but mysteriously, they never appear. THOSE OF YOU WHO CAN ORDER YOUR OWN PARTS AND SUPPLIES ARE LUCKIER THAN YOU THINK!
Never enough advertisers: Just through that in their because I was on a role. 
Please help!
The "skip" problem sounds like a malfunction that would be covered under warrantee.
Slides jamming is often due to the quality of the slide mounts and trays. Do certain types of mounts tend to jam more? Are any bent or distorted? Are "off-brand" trays being used? Best trays are the 80-slide units sold for professional AV applications.
Lamp life: a never ending battle between getting a bright image vs. getting long lamp life. Lower lamp voltage or "long life" lamps tend to lower brightness. Consider using a smaller image (longer focal length lens) to get a brighter image. Be sure the projector is well vented to ensure adequate cooling. Don't expect to get a bright slide image if you are trying to fill a 20-foot high screen that needs 5000 watts of xenon lamp power to light properly!
Advertisers: Can't help there. But it does sound like you are making your own slides, so you have some control over the quality of the slide mounts and trays.
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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
To John Pytlak or anyone else who may know: I am interested in medium format (120 rollfilm) photography and am interested in projecting slides shot in this format. Does Kodak make a projector for 6 X 6 slides? Can anyone made any recommendations? I have never seen one in a shop here - come to think of it, I have never seen one at all (domestic/semi-pro, I mean).
The biggest problem I have is with bad trays. The metal disc must turn with little binding. The EK's are very forgiving, but things do happen.
Sometimes if there is a steep angle to the screen, the slides will not drop into the gate properly and stick.
Are your slides good and flat?
I get 20-30 hours from Apollo lamps using the regular brightness settings, and 15-20 at the high setting.
The Kodaks preform as well as the EK III's, but have much quieter fans. I suspect that this is because the III's are a commercial grade, and the 4600's are more consumer oriented.
Considering how they work, I am amazed that they dont fail more than they do, and I'd hate to get a body part caught in the slide tray pusher. I've seen these break the teeth off of a defective tray.
------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
Thank you for your posts on this subject. In truth, I'm not sure if all the slides are good and flat, but I'd say they are. I'll look at John's sites and go from there.
Thanks,
Aaron