Well that's the point: the 6th is very much a finale driven symphony. Thus, the finale is almost a symphony on to itself. My suggestion is that you listen to just the finale numerous times. There's an awful lot of music and noise in there.
Before we talk about structure, there are a couple of things that are almost like leitmotifs. One is a loud A-major chord that makes a diminuendo (gets softer), and then changes to A-minor. That signature sound is often times accompanied by the "fate" rhythm in the timpani: tum . . tum . . ta-tum, tum, tum. That "fate" rhythm actually comes from the first movement march, and gets used numerous times throughout the finale as well.
As for the structure, there are several different ways that you could look at it. First of all, there's a slow introductory section that begins it, and a slow funeeral dirge that ends the work (followed by just an A-minor chord at the very end, accompanied by the "fate" rhythm). Hence, while there's plenty of fast music in the finale, it starts and ends with slow music. Even the very, VERY beginning of the finale is sort of a leitmotif: the weird, swirling music in the strings that sounds like the theme music to the old TV show "Fantasy Island" ("the plane, the plane!!). That's a very important leitmotif because it pops up at THE most critical moment in the entire finale. More on that later.
Anyway, one way to try to digest the finale, is to listen to everything that happens up until the first hammerstroke; take a break; listen to the music between the two hammerstrokes ("the wild ride of headless horsemen across the scorched battlefields of Europe" - my description); take another break, and then listen to everything that happens after the second hammerstroke.
The most critical music in the finale, is the music that happens after the second hammerstroke. Everything turns hysterical at the second hammerstroke, then the music gets sucked up into a vortex, which is capped off with a solo gong stroke (doubled with the bass drum, actually). Then we come back to the very beginning of the movement, yet again: the swirling strings and spacey melody that sounds like "Fantasy Island" (the plane, the plane!!!). With me so far? . . Then the cowbells tinkle away, and the deep bells - which are representative of church bells - chime away also. Then we come to the final Allegro (fast) "charge" section. This is the nuttiest section in the whole movement, and it's where Mahler's contrapuntal skills reach their zenith. The allegro charge section leads to a passage that I refer to as, "the false victory parade". It's a parade ground theme belted out in the horns (often times underplayed), accompanied by the "fate" motif in the kettledrums. Then we come to slow section, in major, that sounds like the dawning of new, brighter, more promising day. This is where the entire symphony sounds as though it wants to resolve on A-major, and then just stop.
Instead, we get a smash on the tam-tam (doubled with the bass drum), and come back to that introductory, "Fantasy Island" music once again. This segues to the spot where the third hammerstroke is sometimes reinstated: yet another sounding of the A-major to A-minor chord, accompanied by the fate rhythm in the timpani. This dissolves into the funereal dirge for the trombones and tuba. The end.
I'm not sure how a college music professor would analyze this movement. I don't feel that any traditional explanation is actually descriptive enough. Personally, I think of it as a two-part movement. I think of everything that leads up to the tam-tam smash (large gong) after the second hammerstroke as being sort of a Part I, and everything from there to the end being the Part II.
Here's what happens from start to finish:
Opening "Fantasy Island" music (the plane, then plane!); long introductory passage that is similar to the funereal dirge at the end of the movement; first Allegro (fast), "charge" passage; some music that's reminiscent of the "Alma" theme from the first movement; a hard, allegro push up to the first cowbell episode; first cowbell episode (slow and soft); weird, transitional music that gets us to the first hammerstroke; first hammerstroke - lots of mayhem; "bridge" music between the two hammerstrokes (the wild rid of the headless horsemen across the scorched battle plains); second hammerstroke - more mayhem: swirling vortex music - solo tam-tam smash (that isn't solo, it's doubled with the bass drum); introductory, "Fantasy Island" music, dissolving into second cowbell episode (with church bells joining in further down); final, allegro "charge" passage'; more weird, vortex like music; false victory parade theme, accompanied by the fate motif in the timpani (but not played loudly); A-major music that sounds like the promise of new, brighter day; tam-tam smash (again, doubled with the bass drum); introductory music all over again (the plane, the plane!); A-major to A-minor meltdown, accompanied by a loud sounding of the "fate" motif in the timpani (this is where the third hammerstroke originally was, and sometimes gets reinstated); long, funereal dirge in the low brass, dissolving down to almost nothing (cellos); silence; final A-minor outburst (no A-major); pizzicatto pluck in the strings - game over.
Well, it's not formal, but I don't think that traditional, formal analysis tells you damn thing. I really don't. Hope this helps.
Think of WWI. Think of newsreels of troops charging across the scorched earth of the western front, heading straight into barbed wire and machine gun bullets. That works for me. It's certainly not exclusively about Mahler's own personal insecurities or problems.
