Oil pressure sender

Think my oil pressure sending unit has gone on me. it's pinned at 5.4 bars when started. Tried getting the connector off today after an oil change to try to clean the connections between it, but couldn't get it off. Its a 99. I pulled the red locking clip out (only came out about 1/8-1/4 of an inch) and then tried to remove it but it still wouldn't come off.
What is the key to getting it off?

Are you sure you are at the right unit? It is black plastic right above the OFA on the pass side of the block, with one wire coming off it, I think the size is 1 1/4" wrench to loosen it.

Electric connectors - to releaseUSH TOGETHER, THEN release lock and pull apart. Seems to help on some of them.
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I'll try to push it together first. Thanks