Along the way I discovered that the housing of one of the HV control switches was broken and the HV indicator was in pretty bad shape.  A fairly detailed search of the Internet revealed a switch that looked like a good replacement candidate.  I ordered a couple of samples and checked them out.  The company is EAO, and the switches are distributed by Newark Electronics.  The good thing about Newark is that there is no minimum buy, at least for stock items. I put a post on the reflector and 12 other people joined in.  I ordered over $600 worth of switches, lenses and accessories.  The main hitch with the EAO switches is that the standard engraving font does not match the original switches.  I have developed a local engraving source and have a supply of engraved Red and Black lenses.  Here’s a picture of the replacement switches mounted on my 30S-1 front panel.  The picture shows my 30S-1 front panel with one old switch, one new switch, and a new indicator mounted. The replacement switch is a sample and therefore does not have the engraving.

The major differences between the original and replacement are:

The black body around the switch and indicator is only about half as tall as the original. Where the body of the original switch is flush with the front of the button, the new switch button sticks out beyond the body. For this reason I recommend purchasing sets rather than single components.

They fit in the existing holes except for a small collar around the base of the switch/indicator which is about 1 mm tall. This causes the switch to stand off the front panel by about 1 mm. It is barely noticeable and actually looks quite good. I originally thought that this collar was the part of the switch that fits the specified 16 mm (30S-1 is 15.5 mm) panel hole. On measurement, however, the collar is 16.2 mm so I think the switch is supposed to mount this way. If you don't like the look you can do one of two things - grind off the collar or ream out the front panel. I think I'll leave mine alone.

There is a locating tab which just misses fitting the slot in the front panel. You can either drill out the slot (this will in no way affect operation of the panel with original switches, they cover this hole up) so the locating tab will fit in the slot to keep the switch from twisting when you tighten it up, or you can cut the tab off. On my original panel and switches, the tab/slot arrangement does not work well enough to guarantee that the switch will be aligned parallel with the panel edges or other switches. I cut the tabs off of the sample switches.

The replacements are deeper than the original switches and indicators by about 1/2" but on my 30S-1 there is adequate clearance behind them so that this is not a problem.

Here's a picture of my front panel with the replacement switches and switch guards mounted. If you paint the guards black, they look more like the original switches.

Here's a closeup of the switches without the guards.
 If you need switches and/or an indicator, you can order them from Newark.  A new indicator with two old switches might look OK.  Here is a table with the EAO and Newark parts numbers.

Newark #             EAO #                                                         Description
50F8257         31.121.025                     Series 31 Rectangular Switch, Snap Action, Momentary
50F8263         31.040.005                     Series 31 Rectangular Indicator
50F8264         31.901.2                         Series 31 Rectangular Lens, Red
NS/Order        31.901.0                         Series 31 Rectangular Lens, Black
NS/Order        31.963.1                         Bulb, 14V
50F8269         02.905                            Lens Removal Tool
50F8270         02.906                            Lamp Removal Tool
50F8273         01.927                            Series 31 Rectangular Protection Guard

The black lenses are not a stock item and a minimum order charge applies.  Also, as I mentioned above, the factory engraving is not the right size.  For that reason, I have ordered some red and black lenses and had them engraved.  I will sell a two-lens set (the engraved lenses only -- order a blank lens for your indicator from Newark) for $20 shipped (CONUS).  Additional sets in the same order are $10 each.