I haven't used my bell & Howell 16 mm 2685 projector in years. What should I do befor I fire it up

Question edited for clarity, 'Howard' to Howell :>D
Question moved from Cars and Trucks category.

It will be a slipping drive belt.

https://www.google.com/search?q=bell+and+howell+lumina+1.2+projector+drive+belt

The silver knob above the leg knob on a Bell and Howell 455A movie projector is the speed control knob. This knob is used to adjust the speed at which the projector runs. The projector has three speeds: 16, 18, and 24 frames per second (fps). This knob can be used to match the speed of the projector to that of the film being projected. The user can switch between the speeds depending on the format of the film they are using. When the projector is set to the right speed, the motion in the film will appear smooth and fluid, with no stuttering or jerking

It is an auto-load projector. Video here.

https://www.google.com/search?q=bell+and+howell+456a

Your manual is here

Bell & Howell 456A - 256Z - 456X - 456XF

https://issuu.com > filmmaker8.com > docs > bell___ho...
Apr 4, 2016 - Bell & Howell 456A - 256Z - 456X - 456XF - 456XP Projector Service Manual.

Free PDF.user manual for a 456A dual autoload - Bell ...

https://www.fixya.com > ... > Cameras > Bell & Howell
Jan 20, 2019 - Looking for a Owner's manual. For a bell & Howell 456A. Projector. Address is [email protected]. Posted by ...

I am looking for a Free PDF user manual for a Bell - Fixya
Nov 19, 2019
How to thread a Bell & Howell 456A Dual 8 projector? - Fixya
Nov 18, 2019
Manual for bell and howell autoload 8mm projector model471A
Nov 20, 2019
SOLVED: Owners manual.for.bell and howell projector. - Fixya
Aug 1, 2018
More results from www.fixya.com

Bell and Howell Autoload 456 How To Use Manual ...

https://www.manualslib.com > ... > Autoload 456
View and Download Bell and Howell Autoload 456 how to use manual online. Super 8 / Regular 8 Compatible. Autoload 456 projector pdf manual download.

Purchase it with a used Bell & Howell projector on ebay.

Example:

https://www.ebay.com/p/Vintage-Bell-Howell-253-AX-8mm-Film-Projector-WORKING-253AX/665882341


Vintage Bell Howell 253 AX 8mm Film Projector WORKING 253AX eBay

Look it up in the manual

You can download a manual for almost any equipment by Googling the make and model followed by the word Manual, then follow the appropriate link(s).

https://www.google.com/search?q=bell+%26+Howell+TDC+headliner+303

Manuals are available at nominal cost.

https://www.etsy.com/ca/listing/1146809448/bk6-bell-howell-tdc-headliner-303

https://www.google.com/search?q=bell+%26+Howell+TDC+headliner+303+manual

..

go on line to bell & howell site and down load service manual or operators manual.

Check this Website and see if one of the manuals doesn't give you the answer:

http://www.paulivester.com/films/projector/BH273man.htm

manual for Bell Howell 456 super 8 mm dual movie projector