oke, so what fixed it for me (and maybe i was supposed to do this)
Was to enable chromie time, do the first few tasks of the campaign ( up untill Suspicious Shipments) and now the The Legend of Mechagon is available!
So I've done this on a bunch of alts. It's slightly different for Horde and Alliance but roughly the same. You're talking about Alliance but it goes like this:
1. Enter Chromie Time for Legion
2. Use the Skip to go to Dalaran (assuming you've got this unlocked)
3. Hand in the quest and get the Dalaran Hearthstone
4. Go back to Stormwind and pick up BFA bread crumb quest outside the bank. Note: the reason you do Legion above was in trying this a few days ago the BFA quest just didn't show up until I did something in Chromie Time and I wanted the Dalaran HS anyway. There may be other ways and it's quick;
5. Go to the Castle and listen to the RP
6. Go the SW Harbor and skip the intro scenario. You are now in Boralus
7. You ahve to be shown around. This requires going to the ferry, bank, the inn and the flight master;
8. Go meet Cyrus in the Harbormaster's office. This will trigger a cutscene you can skip;
9. Listen to the RP
10. Open the mage portal to SW (Sanctum of the Sages)
11. Go back to Cyrus and hand in that quest
12. Take the next quest (A Nation Divided?)
13. Choose Tirargarde Sound on the map (your only option at this level)
14. Hand in both quests
15. Do the quest next to Cyrus to shoot the barrel. Not sure if this is strictly necessary but it takes 5 seconds.
At this point, you should have the Legend of Mechagon on your map (next to the flight master). The rough steps are:
1. Go to the vault in Tirargarde Sound
2. Repair the machine and go through the RP
3. Go back to Boralus.
4. Recruit your team
5. Embark to Mechagon from the bridge. Note: the quest marker is wrong here. You can miss the trigger if you fly right to it. The trigger is on the bridge.
6. Congrats. You're in Mechagon.
7. Go report to the guy by the dungeon
8. Take the ride to the Junkyard Depot
9. Do the 3 quests. The guy will give you 2. One is from the rig you have to repair.
10. Do the next quest to put up the Rustbolt Resistance logo.
11. Report back to the town and hand in the quest.
12. Skip the tour.
13. Choose the option to skip the Mechagon dungeon run. You should get an achievement progress thing here. Congrats, you can now do the daily quest. This is your main source of RR rep.
14. Take the quest next to the crafter to make a Scrap Grenade
15. Learn the crate blueprint
This and Mechagon in general is now SUBSTANTIALLY eaiser with TWW because you have Dragonriding. This was such a PITA in DF with ground mounts only.
In making the rings IME you will be limited by Galvanic Oscillators and your main source is the daily quest. Try and do ~6 Mechagon chests per day. These can sometimes drop GOs and Coils. By the time you get to Revered RR to make the Extraordinary rings, you'll probably have enough mats to make 4-5. You should get a pair that way (ie sometimes you get a trinket with min level 50).
You might also want to get the extra 10% rep buff before the Mechagon part by doing a TW run for the anniversary extra buff. But, like I said, you'll be limited on GOs not rep.