<!-- from fixya rte -->Troy-bilt service manual download - Troy-Bilt 4-Cycle Curve Shaft Gas String Trimmer #41ADT41C966

SOURCE: Troy Bilt Trimmer 75SS stalls at full throttle. new gas

Hello. Let me assist you. Since your trimmer runs but stalls at ful throttle it is telling you that there is a fuel problem. Not enough gas is getting through the carbeurator to satisfy the engines needs on full throttle. Most likely the carbeurator is gummed up. A common problem. Let's see if we can un gum it by getting a can or carbeurtor cleaner. Go to any auto parts store and talk to the clerk about your need.

SOURCE: how do i install more string? Lost manual

Hi,
I have the same trimmer and I fixed the problem for good by getting a shakespear line trimmer head to replace the original faulty design,it also has 4 line rather than 2 so it cuts better. It costs about $15.00
see link
http://www.lowes.com/lowes/lkn?action=productDetail&productId=120473-42694-14548&lpage=none&cm_mmc=search_yssp-_-Unassigned-_-060209-_-Shakespeare%20Universal%20Fixed%20Line%20Trimmer%20Head

SOURCE: How to replace air filter on Troy-bilt TB20CS?

May be air filter but sounds more like your muffler is stopped up. First take the muffler off and see if it runs better without it. If so, burn the carbon out of the muffler and clean the muffler port on the engine. If not, then remove the four screw at the very end and disassemble. The ait filter is in that area. Diagram is located at
www.stollerlawnandgarden.com/.
Click on parts lookup in left hand column.

SOURCE: need a manual for my troy-bllt (new) only

Try the Troy Built site, this may be your model, there are others listed ,

http://www.troybilt.com/webapp/wcs/stores/servlet/product_10001_14102_92351_55009_-1

Good Luck

SOURCE: lost manual for troy bilt weed eater mod#tb514cs 4cycle

I didn't find that exact one either, but recently had to work on my Yard Man 4-Cycle Straight Shaft and used a Troy-Bilt manual for a similar trimmer - worked great.
If you don't find yours at this site, maybe a similar one will work. It looks like the difference is the TB525 receives attachments. If you're trying to fix something right now, here's the manual for that one until you find yours:
http://lawnandgarden.manualsonline.com/manuals/mfg/troybilt/big_red_tb575ss.html