We do have all the available 503 bulletins published online here...
Hover over SUPPORT/BULLETINS link above.
In the dropdown menu, choose SERVICE BULLETINS.
That will take you to the Service Bulletin Finder page ( https://www.rotax-owner.com/en/support-topmenu/service-bulletins )
On that page, under "Select Search Option" click on the button 'By Engine Model'.
under "Search By Engine Model", select 'All Type 503 Engines' from the drop down (its the fourth item on the list there).
Make sure the radio button 'All Document Types' is selected, then click on the Search button.
This will bring you a list of ALL service documents that could potentially be applicable to your 503 engine.
PS:
If you know the date of manufacture of your engine (post the serial number here if you need me to look it up!) then you can filter for bulletins more specific to your particular engine - (service bulletins published before the date of your engine manufacture have already been complied with at the factory...).
This is done by ticking the 'Select Date Range' checkbox and filling in the dates. For example, if your engine was produced 07/2001, you would fill in
From: 07/2001
To: 02/2020 (current month)
