Clinet's Lennox model # EL296UH090XE48C-03 furnace works fine on stage 1 heat, but hits the high limit switch when on stage 2.
The inducer sounds like it's blending nuts and bolts.
Can I upload a video of the inducer motor?
I would expect the pressure switch or even rollout switch to open before the primary limit, if in fact the inducer motor is the problem.
I would check second stage gas pressure and temperature rise. It sounds like the motor will need to be replaced.
If inducer sounds that bad there's good chance it's not pulling proper draft on high fire,which would explain the limit trip on stage 2. Also check for partially plugged secondary hx or venting restrictions while you're at it