Any machinery which has been modified should be made safe prior to its supply, public liability insurance holders have been told.
The warning comes after Standen Engineering, of Ely, pleaded guilty to breaching Regulation 11(1) of the Supply of Machinery (Safety) Regulations 1992 and was fined £800 with costs of £1,726.71.
Furthermore, the University of Warwick pleaded guilty to breaching Regulation 11(1)(a) of the Provision and Use of Work Equipment Regulations 1998 and was fined £3,000 with costs of £2,091.20.
Boston Magistrates Court heard how Gareth Keal, 28, from Boston, was working on a tractor-mounted bulb harvesting machine at Warwick University's horticultural research site when he suffered severe injuries to his arm after being dragged in.
The contraption, which had been imported, was then modified before being supplied by Standen.
An investigation by the Health and Safety Executive found that Standen had failed to prevent exposure to moving parts of the machine, while the university failed to take measures to prevent access to dangerous parts.
Earlier this week, Peter Haste, owner of Hill Farm, Leiston, was fined £1,600 after a worker suffered injuries to his arm in a chainsaw incident.