Partial blockage - please advise on how I tackle this.

[rpm]

Usual culprit is a rim flush just past the pan outlet or in the U bend holding items back until they have disolved

 

[rpm]

Throw a few buckets of hot water down the pan then see if it happens.
Worst case scenario is the pan has to come out

 

[peter lanky]

I've tried the buckets of water already. Is there not any recognised tool to do this job?