LUBA 2/2X cutting height system failure: the dealer's actual root cause

The symptom

The mower can't raise or lower its cutting blades, and reports it in several different ways depending on when it happens: "traversing to task area failed during recharge"¹, an "angle position sensor" or "lift motor disconnected" error, or simply stopping mid-task and refusing to go home. Because the failure often happens unattended, owners frequently report it as a connectivity problem (the mower shows offline in the app) when the actual sequence was that it hit the height fault, entered error mode, sat for about ten minutes, and powered itself off, which is what then makes it unreachable¹.

One LUBA 2 owner saw three of these messages together in August 2024: "Angle position sensor of lift motor disconnected ( 2748)", "The lift motor cannot reach the designated height (2747)" and "The lift motor stalled when descending (2742)". It mowed again after restarts, but the height would not adjust. Another owner's reply describes the same fix as below: take the covers off and clear the wound-up grass from under the cutting heads³.

Root cause: grass compacted under the blade guard

According to the dealer, the overwhelming majority of these cases have one physical cause: grass builds up underneath the blade guard, the disc that sits just below the cutting blades. Every mow cycle compounds it: the mower raises its blades to travel, lowers them to cut, and grass gets pressed onto the top of the guard; raising the blades again compacts that layer further. Repeated over many cycles, the buildup becomes thick enough that the blade-lift mechanism can't reach its top sensor position, and the mower reports it can't complete the height adjustment and stops¹.

How to check: flip the mower over (power off first) and look at how the blades sit against the guard. If the buildup is uneven, one or two blades will visibly sit higher than the others, pushed up by material trapped underneath.

The fix is mechanical, not a settings change: clean the buildup out from under the blade guard. The dealer's broader recommendation for preventing recurrence:

• Mow more often at a lower cut depth, rather than less often with more grass removed per pass. Heavier cuts build up grass under the guard faster, especially in wet conditions¹.
• If starting from tall or overgrown grass, work the height down gradually over several passes instead of dropping straight to the target height.
• New installs should expect several days of the mower "fighting" overgrown grass before it establishes control of the lawn; most height-related error reports the dealer sees are during this initial period.

How to actually clear it: step-by-step

A separate, independent walkthrough gives the actual disassembly procedure for reaching the buildup²:

1. Remove the three Allen-key screws (2.5mm) holding each cutting disc in place. They attach where the disc's plate meets the mower, and can be hard to spot if there's heavy grass/dirt buildup; dig around if needed.
2. With the discs off, you'll see the blade guard's screws/rivets. Removing these lets you lift the top cover of the guard away from grass trapped underneath.
3. Important: the guard's base section must stay attached: it holds a watertight gasket in place. Removing the top cover is fine; removing the base and then washing the mower will let water fill the housing like a bucket.
4. When reattaching, make sure nothing (grass, dirt) is caught in the gasket seal, and that all screws seat evenly so the seal stays watertight.

When it isn't the grass buildup

If the mower has been thoroughly cleaned and the same fault recurs (particularly an "angle position sensor not found/disconnected" error rather than a generic height-failure message), the dealer's diagnosis shifts to the height encoder on the lift-motor board, not a mechanical jam¹. This is described as uncommon relative to the grass-buildup cases, and not something an owner can self-repair.

An owner's case from October 2026 points the same way, from a different symptom. After a firmware update, a LUBA 2 went to the start of an automatic task and never started the blades, although manual mowing worked, and then reported a cutting disc blocked. A Mammotion staff account said in the thread that the logs showed the hardware self-check could not finish when an automatic task starts, and later that they pointed to a sensor in the lifting system. It recommended sending the mower in for service rather than replacing a part from the logs⁴.

Self-check before calling for service: with the mower in manual mode, lower the blade system all the way down and confirm the app-reported height matches the blade guard's actual physical position, then raise it to the top and check the same way. A working system moves the guard to match what the app shows; if the app says it's changing height but the guard doesn't move (or stops well short of the target, e.g. reporting 70 mm (2¾ in) but only reaching 30 mm (1¼ in)), that points to the encoder rather than a jam¹.