Excel Formula to calculate difference in time for specific criteria

I am attempting to calculate the downtime of our Washers.

I have an excel sheet which displays all our cycle information for our Washer Machines.

Column B is the start time of the Machine. Column E is the time difference between one cycle and another. Column J displays either "None" or "General Washer Error".

What I am attempting is to calculate the time between the last successful Washer Cycle (Where J="None") and the next successful Wash Cycle, but only where there is a failure between them (Where J="General Washer error").

I know I can total the E Column, but this will give me an inaccurate total of downtime as it adds all successful Cycles also.

I have attached an image of the sheet for help.

Any help would be gratefully received.

Thank you