The best way of cleaning a pen that has much debris of old ink especially on the writing unit is disassembling the pen and then using a ultrasound device ( like the ones used for cleaning medical instruments ). No problems with Pelikan, Conway Stewart, .... However these parts are sealed on Montblanc, impossible to disassemble. Question: is it possible to put the pen like that in the device without risking to damage certain parts, resulting in leaking or malfunctioning of the pen afterwards?