Nice Surprize During Pre Flight, And A Few Odd Questions

The airplane I just bought gave me a nice little surprise went out to do my
pre flight and noticed that my right rudder cable had some slop in it I did
not feel comfortable flying it with the lack of tension on it so the
mechanic is going to look at it tomorrow. Also what holds tension on the
rudder cables? I know the cost of a new cable is only $80.00 + labor. Is
there any source on the net ware I can find out how the cable system works
on a later model Cessna 150M kinda curious and would like to know my
airplane inside and out. Ware do I find me a factory service manual? I want
to learn every thing about this little 150.