The X-Lab, Troubleshooting Help Viewer doesn't mention 10.7 but it might still help you, especially the Reset Help Viewer part. That procedure worked fine for me in previous OS versions.

Jon

macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365