Your model number suggest that you have a Textron.

Try searching Homelite Textron UT 105074 or UT-10507-2-4-a and see if you have better luck finding what you need.

105072
105074
10507A

All are about the same saw.

thanks hippy. after i posted i did add textron to the search and got "nothing found". i do realize these little saws vary in models but are basically alike.i usually use stihl saws but since the homelite was free i took it. the homelite chain will not tighten.to get the bar off does the entire plastic body need to be removed? i see no other way.

No it doesn't. In the photo the arrow is pointing toward a nut that holds the bar on. Loosen it. On the opposite side of the bar there should be a small adjusting screw to tighten the chain. Once the chain is adjusted the nut are then tightened. Use caution when tightening the nut for you can pull the studs from the saws engine block.

Copy and paste the link for reference.

Page two. Part #1 is the nut.
If you follow the line from the nut to the engine case. You can make out the adjusting screw toward the front of the saw in front of the clutch.

Page 4 the adjusting screw is part #37
A close up is in the box to the right. It shows the adjusting screw just in from of the stud that holds the bar to the saw.

http://www.odref.com/homelite/chainsaw/ut-10507-2-4-a.PDF

thanks again, hippy.did as per your instructions and the process went smoothly. after bar and chain were removed i noticed the sprocket was rather chewed up so i removed the plastic casing and took off the sprocket. i will search the web for a replacement part.

Hippy has you on the right track, but in your internet searches, use model number UT-10507 and you will find quite a few results. Your submodel number is UT10507-4.

I stock most parts for your XL.
If you are still needing info, I can help
Bill