The mast is aluminum, and if your dimensions are similar to mine, the mast will weight between 70-90 lbs.
Look at the base of the mast. It should have a pivot bolts. Some masts have a rounded foot that will allow them to be lowered either forward or aft, my mast can only be lowered aftwards.
The trick to lowering the mast is that as the mast gets lower, you need a greater mechanical advantage to keep it from dropping (until someone can finally reach it, and hold it up).
Two good methods are to use a gin pole, or to get some lumber and put together an A-frame. Google for "unstepping a mast". Several youtube videos and links pop up.
You're right- if you can get the mast down, you can easily make the repairs. This weekend I was shown a nifty tool for measuring shroud tension. It's like a scale, and it's used for tuning your rig. At the very least, you could make sure they're all set to the same tension when you're done. I don't think the tool was expensive.
I do believe that these repairs could be made aloft if you had to, it would just be a hassle. For that, you'd buy a leg harness or a bosun's chair and have a buddy grind you to up the mast using the winch on the side of the mast, or one of the larger jib sheet winches in the cockpit.
Take a line up with you, tied to a bucket and have your buddy on hand to load it up with whatever tools and parts you need to make the repairs.
Take some pictures of the broken parts and the base of your mast so we can help you better.
S/V Old Shoes
1973 Pearson 30 #255