TABLE 1.

Troubleshooting table.

Problem	Possible reason	Solution
Cell death.	Poor cells or tissue preparation.	Use younger healthy culture cells; change vibrotome settings when working with intact tissue.
	Clumps of bullets hitting the tissue.	Place a culture insert over the cells before gun discharge.
	Gas pressure too high.	Reduce gas pressure or use culture insert as above.
	Microcarriers too large.	Use smaller gold particles.
Microcarriers agglomerate after coating with dye.	Dye concentration is too high.	Reduce dye concentration.
	Dye is impure.	Use new methylene chloride.
	Tubing is dirty.	Use new tubing. Blast nitrogen through the tube before making microcarriers.
Gold does not spread evenly in the tubing.	PVP solution is old.	Make a new stock of PVP in ethanol. Use a fresh bottle of ethanol.
	Insufficiently dry tube before loading.	Flush tubing with nitrogen for 5–10 min before loading.
Poor or no fluorescence.	Dye concentration is too low.	Increase dye concentration.
	Dye not coated well enough on the gold.	Make new gold/dye microcarriers.
	Dyes “bleaches” within tissue (fluorescence becomes weaker under observation).	Lower the laser power and increase the gain to limit susceptibility to light damage.
Contamination of cell cultures.	Gene gun is contaminated.	Wash the end of the barrel with 70% ethanol (vol/vol); change the nylon mesh.
	Poor culture conditions.	Improve culture conditions.