In case it helps anyone else, here is my completed script to check the status of the merge replication agent (that was started when the SQL Server Agent started -  and should be running continuously). If the merge agent is found to be stopped a message is logged and it is restarted.

This can be run as a job on the server where the replication agent is running (in my case I was using push subscriptions so the script runs at the Distributor).

declare @TempJobId uniqueidentifier, @TempJobName sysname

set nocount on

use msdb

/* Search in MSDB for enabled replication merge jobs that are scheduled to run when SQL Server Agent starts */

declare TempJobCursor cursor local fast_forward for

   select j.job_id, j.name from syscategories c, sysjobs j, sysjobschedules s where

      j.job_id = s.job_id and

      j.category_id = c.category_id and

      c.name = N'REPL-Merge' and

      s.freq_type = 64 and

      j.enabled = 1 and

      s.enabled = 1

open TempJobCursor

fetch next from TempJobCursor into @TempJobId, @TempJobName

while @@fetch_status = 0

/* Found a matching job - check its status */

begin

   exec ('declare @TempStatus int

         select @TempStatus = current_execution_status from openrowset(''sqloledb'',

            ''server=(local);trusted_connection=yes'',

            ''set fmtonly off execute msdb.dbo.sp_help_job @job_id=''''' + @TempJobId +

            ''''', @job_aspect=''''JOB'''', @execution_status=4'')')

   if @@rowcount = 1

/* Job found to be in the idle (not running) state; log an event and restart it */

   begin

      exec ('execute sp_start_job @job_id=''' + @TempJobId + '''')

      raiserror ('Watchdog: Restarted Merge Replication agent %s', 0, 1, @TempJobName) with log

   end

   fetch next from TempJobCursor into @TempJobId, @TempJobName

end

/* Clean up */

close TempJobCursor

deallocate TempJobCursor

set nocount off

HTH

Richard