The simple answer, practically speaking: there is no such thing. Now to explain:
If you could find anyone in the civilized world born in any of the past 125 or more years leading up to the most recent 24 (or less) years, he or she would be able to effectively "recite" any such manual in a little as 5 or fewer brief, easy-to-understand sentences; so why endure the grief of a fool's mission to find what wasn't worth not losing to begin with. Consider these long since known facts:
- There is no such thing as a turntable or record changer produced by any mfr named Sylvania--just like more commonly branded items such as light bulbs are not made by Sylvania (since it expired as a major TV producer long decades ago but not before selling rights to use of its once-famous-among-the-impressionable brand rights and good will.
- There is nothing apart from a branding to disitinguish any basic (or even advanced...word used loosely) turntable or changer from any other such item anywere in the world or any time since the mid 20th century. So buy any manual if you can find one, or write your own...all the same.
- Whoever it might be, among the one to a few manufacturers, who are responsible for producing and branding "your" turntable, would be very highly unlikely to have produced (rather than sublet a supplier to provide) a manual...because manuals are overhead and overhead expense reduces profit already at slim margin.
- Once you have figured and accomplished the few simple steps to operate one of the simplest devices ever known to mankind--a washing machine can be an order of magnitude or more difficult to fathom--you will wonder to your own amazement (that's classic, not contemporary amazement) why you would ever want to memorialize the steps you just took and didn't take.
So here's your manual, which I offer without copyright for you to save and print out for you, your children, and your children's children (until something better than vinyl comes along):
1. After raising cover, place record onto spindle (if turntable) or drop-spindle (if changer) and rotate/lower hold down arm (if changer).
2. Set or don't set platter (that's the turning table) rotation speed depending on record type/speed marked on record package.
3. Slide START lever to its stop point; release; and wait (if changer) or toggle on table rotation and manually place tone arm and stylus onto record outer start landing or groove (if turntable).
4. Wait until sound stops indicating playback end, stow tone arm, and remove record (if turntable); or lift and swing hold-down orm and remove record (if changer).
5. Supplemental: repeat; or turn off platter moter power (if turntable and not changer).
Now I won't be able to sleep for fear of the waking in the morning wondering what it would be like to have never encountered the enigma that is record player operation. Yikes, you are a brave one.