1. Set the dish elevation to that for 19.2E
2. Fit only one LNB, at the focal point (ie not offset)
3. Select Astra 1 and finish aligning the dish
4. Do not move the dish again!
5. Offset the original LNB and adjust it on the rail for 28E
6. Add the second LNB and adjust it on the rail for 13E
Spot on. But as I sense that even getting 19.2E feels like a challenge, allow me to elaborate on that bit:
My LNB arm is pointing at 19.2, I tried to get the LNBs in offset to point to 28.2 and 13 but could not get any lock. Tried also with one LNB close to the focus but could not get 19.2 lock, but that is probably because the angle I set for the dish was for astra 2 (25°).
When aligning the dish for 19.2E, you can't rely on dishpointer.com or alignment apps to be precise enough.
It will give you a good starting directions, but the dish needs to be adjusted carefully.
And that needs to be done by hand, and fine-tuned in order get maximum signal - this is important for multi-LNB setup.
A good thing, though, is that 19.2E is extremely strong, so it is one of the easier sats to adjust to,
You need to attach a meter, a low-cost beeper, or even an STB that you can observe while adjusting the dish.
Do you still have the single-LNB bracket that presumably came with the dish?
Then put that on instead of the multi-feed, and adjust dish to 19.2E.
(If not, then it is alright, it it still doable by putting an LNB on the bracket just snuggling along side of the arm, but put the LNB on the *LEFT*-hand side of the LNB-arm when looking from reflector towards the LNBs. This is because you want the dish to be pointing roughly mid-way between 28.2E and 13E, which is something like 20.5E. For this to work, 19.2E should be slighty to the *right* of the arm, so the LNB goes on the LEFT as the reflector is a mirror - as a33 says above.)
Steps to adjust
If you use meter or STB, choose a frequency in in the stronger groups, e.g. ZDF on 11362H.
If you use a beeper, then find strongest signal close to the dispointer direction, then fine-tune while looking at the signal bars on the telly.
(If you can't see the telly from the dish, have someone watching the telly and either shout or use mobile phones with a hands free - don't fall off the ladder!.)
1. First you set the elevation as per bracket (this requires the pole to be more or less plumb). For 19.2E.
(You've already done that.)
2. You now loosen the backmost brackets, and point the dish in the general direction that dishpointer tells you to. For 19.2E
(You seem to have done this too.)
This will probably not give you a signal straight away, but it's a starting point.
3. Now you move the dish in a slow movement left and right of where dishpointer told you to look.
The signal strength should go up and down, and you need to centre on the strongest peak.
4. When centered, fasten the bolts so the dish doesn't easily move left or right (this needs to be fairly tight on the Triax).
5. Now maximise the signal strength by adjusting the elevation of the dish.
Do this by loosening the elevation bolts on the bracket, and then adjusting the elevation / angle of the dish until you get an even stronger signal. Then tighten the elevation bolts again.
6. Note that on the Triax this requires a bit of step-wise approximation, as the angle invariably changes slightly when you tighthen the elevation bolts.
You should now have a dish poiting at 19.2E, and you should be able to receive most channels there.
Tighten all bolts on the dish bracket, and if you put the single-LNB bracket on, now put the multi-LNB one back on.
Now continue as Lazarus says above.