A couple additional points are worth adding. Special equipment fuses are labeled A, B, C and D. These are held in pairs at the ends of fuse box. Some versions do not have either or both pairs (some Euro variants and US 230 and 240D have crank windows, manual sunroofs and may not use auxiliary fan). On earlier model years, spare fuses were stored in foam rubber inserts (above and below threaded inserts). These deteriorate with age and can be equated with rubber tubing or simple cardboard sleeve. Keep two pairs of white and red spare fuses in these locations, blue spares can be kept in toolbox or glove compartment, (they fail less often). When servicing fuse box, always check the 10 mm mounting nut to be sure it is snug.

Idling voltage test should be done under full-load condition: turn on headlamps and set blower motor to high speed, (blower switch fully clockwise for Climate Control I - three knob system; Defrost setting for Climate Control II and III). Testing must validate voltage and current values, the latter is greater with lighting and motor loads. Comparing unloaded and fully loaded voltages can illuminate weak alternator / regulator output.

It is advised to also fill cylinder head through heater hose - disconnect at firewall end - before starting. Air pockets in cylinder head can increase likelihood of overheating after coolant exchange. Getting coolant into head is critical to assure proper cooling and avoiding air-locked system. When jacking up is not feasible, park car on a hill or front wheels on curb to elevate vehicle. Be very careful when topping coolant during refill as air pockets can cause violent releases of steam and fluid (visualize erupting volcano).

Tips: Be sure to replace the clamps with new worm-drive type having combination hex-slot screw heads. These are far superior to original type. Also be sure to orient the clamps so screw heads point toward front of car and next to the cylinder head. The latter is necessary for proper clearance as air conditioning bracket sits adjacent to thermostat housing on some versions. Take time to carefully situate the hose clamps as they are almost impossible to access once compressor bracket is in place. Also take time to clean metal surfaces to which the hose connects - lightly sand or scour with metal brush to remove deposits - assuring proper seal is important before assembly.

Removal of ashtray is also necessary to access the lamp which illuminates the cavity. After taking ashtray out, remove two Philips (+) screws, then separate metal cover from plastic housing. Next to the lighter housing is light socket. It holds a 12 volt, 2 watt, T2 bayonet base, #1272 lamp. Push, then twist lamp to remove. Clean copper terminal at side of socket as well as moving contact on side of ashtray housing. This lamp is same type as used for automatic shift indicator. This is one of the most overlooked lamps in a W123 chassis. Tip: while metal cover is removed, clean and scrub ashtray, it is much easier to access this way.

This model is also known as the Apple Studio Display 15" LCD.

Removing graphics (video) card is not necessary. Also, removing the clips which retain heat-sink can be accomplished by using a flat-blade (-) screwdriver to carefully pry them from the finned aluminum assembly. Other than these two suggestions, guide is succinct and accurate.