Multi-part identifier could not be bound on UPDATE SQL statement with multiple JOINs

I am at a loss here.  I have read multiple posts on this, but I can't seem to figure out where I am going wrong.  The only thing I can figure is that I am somehow not stating the INNER JOIN correctly.  The JOIN should be that the two tables must match by LOC and ITEM in order for the update to take place.  Here is my SQL attempt at doing this UPDATE:

UPDATE [SL01 MW01 Clean Up Records]
SET New_Sources.dbo_a1_5_SRC1_ID = [SL01 MW01 Clean Up Records].[SRC1_ID], New_Sources.Vendor_id = [SL01 MW01 Clean Up Records].[Vendor_id]
FROM [SL01 MW01 Clean Up Records]
INNER JOIN New_Sources ON ([SL01 MW01 Clean Up Records].dbo_a1_1_LOC = New_Sources.LOC)
AND ([SL01 MW01 Clean Up Records].ITEM = New_Sources.ITEM)

I just keep gettiing the following error message when I execute it:
Msg 4104, Level 16, State 1, Line 1
The multi-part identifier "New_Sources.dbo_a1_5_SRC1_ID" could not be bound.

Help please.

Thanks,
Matt