Sites like The Bus Station or specific UK bus enthusiast forums often have members who share digitized PDFs of out-of-print manuals for older M-series Solos.

Most Solos use the Allison 2100 Series or WTEC systems, which require their own diagnostic guides. Where to Find the Workshop Manual Links

Covers the stainless steel integral structure, braking systems, and electrical multiplexing.

Depending on the year, you will need the specific manual for the Mercedes-Benz OM904LA or the Cummins ISBe engine.

Specifics on the Meritor or similar braking assemblies used in the low-floor chassis.

If you are searching for a manual to perform specific repairs, ensure the documentation covers:

The Solo relies heavily on electronic control units (ECUs) for body functions.