None of the discussions seem to fit this situation completely.
Drawings initiallly created in SW 2014 do not have any issues with symbols, particularly <MOD-DIAM>.
Drawings initially created in previous versions do not always display, print, or export correctly, even when saved, and even when the sheet format is changed to one created in 2014.
A drawing created in SW 2012 or SW 2013 is opened in SW 2014. Where the Ø appeared on the sheet, it displays as <MOD-DIAM>. Clicking on the dimension sometimes makes it temporarily display as a Ø again, but as soon as the drawing is printed or exported to a .pdf, the hard copy or .pdf shows <MOD-DIAM>, even if it was correctly displayed in SW as Ø at the time of printing.
Deleting the dimension and adding it again does not prevent this. Deleting the <MOD-DIAM> in the Dimension Text window of the Dimension pane and clicking on the Ø to re-add it does not prevent this. The ONLY way to fix old drawings is to start over and completely re-create the drawing in SW 2014, or to replace <MOD-DIAM> in the Dimension Text box with a Ø, manually, using ALT+0216.
Seemingly related, in any drawing initially created in a previous version, even when updated and saved, if a note is created and the Add Symbol button in the Text Format box of the Note pane is clicked the message "Symbol library file (GTOL.SYM) is missing. Use Tools > Options > System Options > File Locations to specify the file location" appears. Following this path, the folder for Symbol Library File is C:\ProgramData\SolidWork\SolidWorks 2014\lang\english. Using Windows Explorer, it is confirmed that the folder contains GTOL.SYM.
In any drawing initially created in SW 2014, the Add Symbol button works fine and the Options > System Options > File Locations show the exact same path for GTOL.SYM, but it actually works for these drawings.
Only SW 2014 is installed on this computer; all previous versions were removed. I have not experienced this issue in any previous versions of SolidWorks.