Don't know If this has been mentioned, but.
We had a shuttle program.
If we separate the telescope in three parts.
1) Mirrors and Support Structure.
2) Main instrumentation, power, controls, solar panels
3) Propulsion system, (final position and station keeping), backup solar panels
Could not the 1st (mirrors) part have been launched and assembled by the
Space shuttle program. It seems to be the most likely place
to have terminal anomaly, with this design.
Number 2 and 3 could be launched separately on rockets, and timed so that all 3 parts are orbiting as loose group
Another shuttle launch could be used to gather and assemble all 3 parts, and it might give it some help putting it into proper orbit.
Sure it might be expensive, but much higher chance of success, than the
current strategy.