Motorola 259M

[marty59]

You may not be successful in finding a replacement but others may chime in. Has this unit been re-capped/refurbished? If the only problem is turning on-off then I would suggest shorting out the switch and using a power strip to operate with. On many of my old radios I will switch them externally than to increase any wear and tear on a part that is difficult to replace.

You can do this temporary if you wish until a suitable sub/replacement comes along at the least and still be able to enjoy it.