Sourcing in-line fuses 12V 3A/5A
Stretching spring may not ensure adequate contact and create problems and or burned contacts in fuse holder.
Try local electrical supply wholesaler servicing commercial accounts. They'll usually sell to walk-ins but might want cash. A lot of test equipment still uses the glass Buss-type fuses. Even in my small town two different wholesalers stock ranges of this type fuse, 'large' and 'small' physical sizes, in amp ratings from 1/4-amp to larger than any of us will need. Good luck.