National Archives at Kew hold the surving personnel WO 12 and muster pay/roll documents WO 10 for Regiments of the British Army.
The 53rd Foot Regiment have ,i am advised by the Shropshire Reg museum a relatively small % of soldiers records surviving. These are searchable for names on the National Archive website, but I have no idea if all of the names of the % remaining are all entered. You cannot view any specific documents online , but the record is available on micro-film for anyone who can get to Kew.
The muster payroll records for the 53rd are also available at Kew but limited data is available to determine exactly what document you need to look at, but I know they are available for the period 1822 - 1845 ( and I assume immediately before and after these dates ). These records are very interesting, and if you have someone in the regiment he is almost certain to appear, you can determine location of enrolment, pay, march details, discipline record, appointments and discharge detail. It will detail all deserters and from what i've seen punishments including executions, so start looking with an open mind because you just do not know what you will find.
I suspect your soldier will not feature in the regiment records with my family interest, but on my next visit will look in the earliest book of my interest to check( that is 1824 )
Please feel free to contact me seperately I have a Genes reunited site ,search for Gabriel WELLS born 1803, and I amongst the 2 researchers with that name on my tree.
Otherwise pjwells@talk21.com