RT11 boot block 0 words ?

I would like to use the vast knowledge of this community, as a brief search through the calssiccmp archive gave no answer ... I can't get RT11 booted anymore on my 11/34. To isolate the problem I have only one RL02 drive connected to the RL11. Before I start the M9312 monitor, I dumped 00005's in the memory locations 000000 thru 000070. Then I started the M9312 monitor (at 165020), and enter "DL" on the prompt. I loaded the RL02 cartridge, that I always use, first, of course. The READY lamp of the RL02 drive flashes briefly off/on once, and then the display on the 11/34 console shows (address) 000004, and the RUN lamp goes off. Examining the memory shows that location 000000 contains 000240, and all subsequent locations contain 000000. So the memory locations are written ... Is the first word (000240) the first word of block 0 of the RT11 bootstrap? I hesitate to load the XXDP RL02 cartridge that I have. I never made a copy (stupid, I know), and I am afraid to loose it ... thanks, - Henk, PA8PDP. This message and attachment(s) are intended solely for the use of the addressee and may contain information that is privileged, confidential or otherwise exempt from disclosure under applicable law. If you are not the intended recipient or agent thereof responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by telephone and with a "reply" message. Thank you for your cooperation.