I am from Pune India I have an old analog Marklin HO System . I would like to know hoe to clean these signals AS THEY NOW DO NOT WORK SMOOTHLY. iS ip Alcohol 99% the right cleaning solution. After removing the cover what part do I clean. Can I just test them by connecting them to a Marklin transformer through a 7072 Blue Box to test each Signal. I must admit that I have not used them for a long time and we generally have a lot of dust in our country The Signal numbers are Marklin 7039/7040
7041 etc.
Thanks,
Kumar Vartak India

Thanks Mikey ,
Will try on one signal first Is IP alcohol the right cleaning agent
Kumar

Hi Kumar

Unless messed-up signals the frequent cause of malfonction of Märklin signals like 7036, 7037, 7038, 7039, 7040, 7041, 7042 is because one of the coils over-heated and deformed the inner rectangular passage for the moving core. In this case, the real cure is about changing the coil (cannibalizing another signal).
Another possible cause is someone tried to lubricate the signal (dry oil = friction)
In most cases, access to the coil is about straightening a metal tongue at the rear of the core conduit (inside the rear coil).
On some models (depending the year) the front of the coil is latched by a tiny wire to be removed prior to opening.
In most cases, the wires need unsoldering so better take a picture beforehand.

Here is an extract of a maintenance manual from Märklin in the period 1973-1980

Notice the soldering nuts (red) and the latching nipple (violett) to latch the coil at front (near contacts)
The Märklin reference of the spare part was 41108

Some spare parts may be found on ebay Germany like this
https://www.ebay.de/itm/38692484...D%7Ctkp%3ABk9SR6COz6f5Yw
Cheers
Jean