Some points can't be shown all-at-once. If, for example, the Midford-Wellow tramway can't be seen, scroll down on the LH pane and click on next page. (See here for a pic.)
Unfortunately Google maps can only accept 100 points so the Timsbury basin tramways details needs to go on another maps page. See below.
View Larger Map
Any probems? If you are sure that your kit is up to it,then most problems, especially if they suddenly manifest themselves, can be resolved by:
1. Using the reload or refresh button on the browser.
2. Flush the browser cache (Details)