Pulling the alternator is not a difficult job on a N/A 240. Remove the negative lead to the battery. Loosen the 13mm nut that locks the tensioner arm in place ... loosen the 10 mm tensioner long bolt until you can lift the alternator up enough to remove the belts. Remove the spade red wire, large red and blue ground wire from the back of the unit. Remove the upper 13mm nut and push the bolt out of adjustment arm and alt body. Remove the lower long mounting bolt and nut , it's also 13mm and pull the alternator out. I usually run my 240s up on some Rhino ramps and remove the belly pan for better access to the lower mounting nut and bolt. Your alternator may only need some new brushes/voltage regulator to get well. Easy to replace ... I like to carefully clean the slip rings with alcohol on a small patch, then clean all the connections with scotch bright and put a little di-electric grease on the connections before installing a new VR and hooking the leads back up. If the VR has been working well but needs new brushes I usually solder in a new set.($3) Replacing the VR/Brushes as a unit is also an option. I've had good luck with a 20 buck Germany Hugo 14.5 volt VR. It's also a good time to replace the rubber mount bushings that hold the alt in place. (three total)They can collapse and cause the Alt (P/S Pump and A/C compressor as well)to be cocked ... throwing the drive belts out of alignment. Lots of belt noise and unnecessary stress on various bearings. Poly bushings here can last much longer than OE rubber. You should get a multi-meter and check out put to the battery terminals once everything's back together. It should read approx 13.5 and 14.5 volts when idling. If lower than 13.5 ... check out put from the large red lead at the alternator back ... positive meter lead connected here ... black (neg) to gound. If it's still lower than 13.5 check the alt ground by measuring voltage off the alt case (red lead touches alt body black still at ground) There shouldn't be any more that .5 volts ... if there's more the alt ground is bad. If you read good voltage off the back of the alt ... there's a problem in the wiring between the alt and the battery. Hopes this helps.